a2ps: update to 4.15.

* Noteworthy changes in release 4.15 (2023-03-07) [stable]
* New maintainer, Reuben Thomas.
* Features:
  - Replace the 'psmandup' utility with simpler 'lp2' to directly print
    documents to a simplex printer.
  - Remove the outdated 'psset' and 'fixnt', and simplify 'fixps' to
    always process its input with Ghostscript.
  - Use libpaper's paper sizes. This includes user-defined paper sizes
    when using libpaper 2. It is still possible to define custom margins
    using "Medium:" specifications in the configuration file, and the
    one size defined by a2ps that libpaper does not know about, Quarto, is
    retained for backwards compatiblity, and as an example.
* Documentation
  - Remove some obsolete explanations.
  - Reformat --help output consistently to 80 columns.
  - Some English fixes.
* Bug fixes:
  - Avoid a crash when a medium is not specified; instead, use the default
    libpaper size (configured by the user or sysadmin, or the locale
    default).
  - Fix some other potential crashes and compiler warnings.
  - Fixes for security bugs CVE-2001-1593, CVE-2015-8107 and CVE-2014-0466.
  - Minor bugs fixed.
* Predefined delegations:
  - Remove support for defunct Netscape and proprietary Acrobat Reader.
  - Add lpr wrapper for automatic detection of different printing systems,
    including CUPS support.
* Encodings:
  - Use libre fonts for KOI-8.
  - Composite fonts support.
* Build
  - Update build system to more recent autotools and gettext versions.
  - Build man pages in a simpler and more robust way.
  - Document runtime dependencies.
  - Minor code quality improvements.
  - Minor tidy up and removal of obsolete code.
  - Require libpaper.
  - Remove OS/2 support.

(wiz)