mandoc: update to 1.14.6.

Changes in version 1.14.6, released on September 23, 2021

    --- MAJOR NEW FEATURES ---
 * mdoc(7): automatic tagging improved in many respects
 * mdoc(7): new .Tg (tag) macro to explicitly mark a place as defining a term
 * man(7): implement some automatic tagging support
 * man(1): let -w without argument show the manpath, like in man-db and man-1.6
 * -T html: wrap text and phrasing elements in paragraphs unless already
   contained in flow containers; never put them directly into sections.
   This helps to format paragraphs with the CSS class selector .Pp.
 * man.conf(5): remove support for the "_whatdb" configuration directive
   that was deprecated in 2015; please use "manpath" instead
    --- MINOR NEW FEATURES ---
 * man(1): switch the default pager from "more -s" to "less"
 * man(1): in the fallback code to look for manual pages without using
   mandoc.db(5), accept files "man<one-digit-section>/<name>.<full-section>"
   in addition to the already supported "man<full-section>/name.[01-9]*"
 * if messages are shown and output is printed without a pager, display
   a heads-up on stderr at the end because otherwise, users may easily
   miss the messages
 * man.cgi(8): add a Content-Security-Policy HTTP header
 * man.cgi(8): switch off autocomplete and autocapitalize
 * mandoc.css: support prefers-color-scheme: dark
 * -T html: add meta viewport element to help mobile devices
 * -T html -O tag: let this pass a file:// URI to the pager
 * tbl(7): implement the "nospaces" option
 * tbl(7) -T html: implement the "a" (em indent) layout specification
 * tbl(7) -T html: implement the "b" (bold) and "i" (italic) layout modifiers
 * tbl(7): support two-character font names in the layout font modifier
 * tbl(7) -T html: support horinzontal rulers in individual cells
 * tbl(7) -T tree: print more details about columns, options, rows, and cells
 * roff(7): implement the .break request (break out of a .while loop)
 * roff(7): support the CB and CI fonts in \f and .ft
 * -T lint: new STYLE message if a file name extension contradicts .Dt/.TH
 * -T lint: new STYLE message about overlong text lines
 * -W style: check .Xr links along the full manpath
    --- RELIABILITY BUGFIXES ---
 * man(1): do not segfault if /tmp/ is not writeable
 * man(1): do not access a NULL pointer when both -l and -w are given
 * makewhatis(8): do not crash when a manpath directory contains
   a symbolic link that points to a directory
 * man(7): fix an assertion failure caused by doubly nested next-line scopes
 * tbl(7): fix a crash when the last column is only reached by spans
 * tbl(7): fix a NULL pointer access in some cases of two spans on one row
 * tbl(7) -T ascii: fix a NULL pointer access on empty data cells
 * tbl(7) -T ascii: fix a NULL pointer access on a line next to a short row
 * tbl(7): fix an assertion failure caused by excessive spacing modifiers
 * tbl(7): fix an infinite loop for some overlapping horizontal spans
 * roff(7): fix a rare case of writing one byte past the end of the input buffer
 * roff(7): do not call abort(3) when \*[.T] is encountered
 * roff(7): fix an assertion failure caused by a macro inside .ce .if
 * roff(7): fix assertion failures for .ti and .po with excessive arguments
 * roff(7): avoid near-infinte output for .ce inside explicit no-fill mode
 * -T ascii/utf8: fix assertion failures caused by excessive spacing
 * -T html: fix an assertion failure caused by .ft in rare situations
 * -T man: fix an assertion failure caused by tbl(7) and eqn(7) input
    --- PORTABILITY IMPROVEMENTS ---
 * rename HOMEBREWDIR to READ_ALLOWED_PATH, allow it to contain more than
   one directory, and explain how to use that for NixOS and GNU Guix Linux
 * configure: stop trying to ask make(1) what the default compiler is
   because that test was too fragile; just use "cc" by default
 * configure: various simplifications and improved robustness
 * configure: only compile compat_*.c implementations that are needed
 * configure: provide feature tests for __attribute__(()) and mkstemps(3)
 * compat_*: sync with upstreams for security, functionality, and style
 * in regress.pl, avoid the non-portable options sed(1) -i and echo(1) -n
 * in the regression suite, avoid file names that differ only by case
    --- MINOR FUNCTIONAL IMPROVEMENTS ---
 * man(1) -h: for pages lacking a SYNOPSIS, show the NAME section
 * man(1): when the first argument starts with a digit, optionally
   followed by a letter, and at least one more argument follows,
   interpret the first argument as a section name even when additional
   characters follow after the digit and letter
 * man(1): with a specific section requested, try harder to find
   the best match; use this order of preference:
   1. The section in both the directory name and the file name matches exactly.
   2. The section in the file name matches exactly.
   3. The section in the directory name matches exactly.
   4. Neither of them matches exactly.
 * man(1): if no tags were generated at all, unlink(2) the empty tags file
   as soon as the condition can be detected and do not pass it to less(1)
 * makewhatis(8): handle both dangling symlinks and .so links
   in manual page directories more gracefully
 * man.cgi(8): for invalid queries and for valid queries returning
   no result, return the appropriate 40x status code rather than 200
 * mdoc(7): let .Dd concatenate all arguments and default to the empty string
 * mdoc(7): convert ".Fl Fl" to ".Fl \-" during validation, improving -T html
 * mdoc(7): improve output of .At 32v
 * man(7): no longer print multiple blank lines before NAME and page footer
 * tbl(7) -T utf8: improved rendering of horizontal lines
 * tbl(7) -T html: in "n" cells, align by padding numbers on the right
 * tbl(7): no longer leak tabulator settings to subsequent roff(7) code
 * mdoc(7) -T html: for .Bl -tag, use "column-count: 1" rather
   than "overflow: auto" to avoid the ugly side effects
 * mdoc(7) -T html: render .Bd -unfilled in proportionally-spaced font
 * mdoc(7) -T html: format .Nd with <span> rather than <div>
 * mdoc(7) -T lint: do not warn about Mdocdate without an actual date
 * mdoc(7) -T lint: do not complain about function types of the
   form "ret_type (fname)(args)", but otherwise check names more strictly
 * -T html: append .html suffix to temporary files to please browsers
 * -T markdown: print a BAGARG message if called on man(7) input
    --- MINOR BUGFIXES ---
 * man(1): do the search for each name independently, and
   show the results in the order of the command line argument
 * man(1): escape shell wildcard characters in name arguments before glob(3)
 * man(1): when asking for a single manual page by name, prefer file name
   matches over .Dt/.TH matches over first NAME matches over later NAME
   matches, but do not change the ordering for apropos(1) nor for man -a
 * man(1): correctly extract the section name from the file name extension
   of gzipped manual page files
 * makewhatis(8): fix file type tests putting wrong data into mandoc.db(5)
 * man.cgi(8): fix section number in the <title> element for preformatted pages
 * tbl(7): correct handling of T& after horizontal rulers in the layout
 * tbl(7): correct column widths if rows have different numbers of cells
 * tbl(7): empty columns are 1n wide rather than 0n
 * tbl(7): correctly calculate required column widths for tables containing
   cells that horizontally span columns which contains "n" (number) formatted
   cells on other rows
 * tbl(7): skip escape sequences when looking for column separators
 * eqn(7): skip whitespace before tokens
 * roff(7): when calling an empty macro, do not clobber existing arguments
 * roff(7): recognize \} on lines closing a macro definition request
 * roff(7): do not throw a bogus warning for "'br\}" and similar lines
 * roff(7): stop generating comment nodes when encountering the first content
 * mandoc_char(7): make \0 (digit-width space) non-breaking
 * mdoc(7) .Bl -column: parse Macro in .It "word<tab>word" Ta word Macro<eol>
 * mdoc(7) -T html: display straight quotes, not curly quotes, for .Qq/.Qo
 * -T html: remove some spurious line breaks, in particular inside <pre>
 * -T html: use <br/> for a space character at the beginning of an input line
 * -T html: use ~%d for ordinal fragment suffixes, reserve '~' for that purpose
    --- STRUCTURAL IMPROVEMENTS ---
 * introduce the concept of semantically transparent syntax tree nodes,
   allowing improved decisions in various validators and formatters
 * move some code out of the giant main() into separate functions
   doing one well-defined task each
 * clearly separate parser state (struct curparse) and formatter state
   (struct outstate), don't mix them in the same struct
 * in the HTML formatter, assert(3) that no HTML nesting violation occurs
 * let html_close_paragraph() close any phrasing context


(wiz)