Log Message:
Update mksh to R40d.

Changes: essentially bugfixes.

  # [tg] New test.sh `-f' option (same as `-C fastbox')
  # [tg] Drop using set -o noglob inside pushd/popd/dirs
  # [tg] Use += more in dot.mkshrc and keep strings shorter
  # [tg] Correct interworking between local and set -A
  # [tg] Fix out-of-bounds memory access on strings of 32 KiB length
  # [tg] MKSH_DISABLE_DEPRECATED (for integrators)
  # [tg, Jilles Tjoelker] test(1) built-in behaves exactly as POSIX says
  # [tg] Move compile-time assertions to Build.sh from misc.c#ifdef DEBUG
  # [tg] Invocation documentation is at the bottom of Build.sh
  # [tg] test.sh: verbosely look for perl(1) interpreter to use
  # [tg] New tests for integers (base 1#36, base unspecified, base OOB)
  # [tg] Correct error paths for typeset -n global state
  # [tg] Deprecate interpreting "010" as octal number, will go
  # [tg] Improvements re. integer handling; more explicit manpage text
  # [tg] Do not use caddr_t on Linux, so dietlibc stops bitching
  # [tg, Jilles Tjoelker] Catch division/modulo overflow 0x80000000/-1
  # [tg] Emacs mode ^O regression fix when the fetched lines are edited