Merge branch '2.4.x' into 2.5.x

Merge branch '2.4.x' into 2.5.x

* 2.4.x:
  Release 2.4.5.
  math/group-parse.c (group-parse): Parse binary-group descriptions.
  math/group-parse.c: Fix copyright notice.
  *.c: Check for ARM64 SIMD before using the accelerated code.
  base/dispatch.c: Recognize `CPUFEAT_ARM_NEON' as requesting ARM64 SIMD.
  symm/t/chacha: Missing test from RFC8439.
  math/t/{mpx,mpmont}: Add some extra tests for flushing out `mul4' bugs.
  math/mpx-mul4-*: Test the `...zc' variants too.
  math/Makefile.am, symm/Makefile.am: Use `--no-install' on oddball tests.
  progs/pixie.c: Don't crash when trying to set an empty passphrase.
  configure.ac, vars.am: Use host-specific link options for test programs.