Update to 2.1.7.

New in version 2.1.7

    * incompatible change: on certain platforms (currently just
      x86-64), dynamic-extent arrays specialized on character and
      numeric types and created without either :INITIAL-ELEMENT or
      :INITIAL-CONTENTS will reflect previous contents of the stack
      instead of #\null (or 0) in all elements.
    * minor incompatible change: SB-SPROF:START-PROFILING no longer
      silently does nothing if the clock is already running. It
      instead stop and restarts with the newly provided options, and
      warns.
    * minor incompatible change: the system attempts to refer to the
      supplied pathname in compiler diagnostics, if relevant, rather
      than the truename.
    * enhancement: new contrib module sb-graph producing graphical
      visualizations of Intermediate Representations of SBCL
      compilation data structures.
    * platform support:
        * improved code generation for unary minus in modular contexts
          on arm64.
        * make the disassembler annotations slightly more robust on arm64.
        * release space back to the Operating System on Windows.
        * improve the test for whether pages need to be committed on Windows.
        * fix a bug in the use of the VPCMPEQD opcode on
          x86-64. (#1928516, thanks to Marco Heisig)
    * optimization: the type of (LOOP ... COLLECT ...), and the type
      of COLLECT INTO variables, is derived as LIST. (#1934577,
      reported by SATO shinichi)

New in version 2.1.6

    * minor incompatible change: COMPILE-FILE does not merge the input
      file's pathname-directory into the output path if :OUTPUT-FILE
      was specified and has a directory that is not :UNSPECIFIC.
    * platform support:
        * improvements to unwind code generation on arm64.
        * on x86-64, accept three operands for vshufpd. (reported by
          Bela Pecsek)
        * on x86-64, improvements to use of popcount
        * improve exception handling on 64-bit Windows. (thanks to
          Luis Borges de Oliveira)
    * bug fix: allow use of macros with improper argument
      list. (#1929623, thanks to Sean Maher)
    * bug fix: COERCE no longer attempts to guess what the user meant
      if they provide a type specifier of a union of types other than
      STRING. (#1929614)
    * bug fix: print a single trailing zero after the decimal point
      for FORMAT ~E if there are no digits remaining to be printed and
      the width allows it. (#883520)

(rjs)