2.4.2-26: Revert the MASM assembler basename in autodetect_compiler

The spaced assembler path is handled in dkml-compiler's compiler-env script,
not in autodetect_compiler, so this change was redundant for the host build
that needed it and is being removed to keep detection unchanged.

+ change the CMake MASM branch back to the full assembler path

2.4.2-25: Fix brew bundle dump exit 127 on macOS hermetic builds

The Darwin host build will be probing for Homebrew on the build PATH while
running the brew commands through hermetic_util, which resets PATH to
/usr/bin:/bin and cannot find brew under a prefix such as /opt/homebrew/bin.
An unavailable brew will be falling through to the existing no-op branch once
the check uses the same hermetic lookup as the commands.

+ change install_reproducible_system_packages to detect brew through the same
  hermetic_util lookup as the brew bundle dump and brew --version commands

2.4.2-24

Fix host ./configure cl-not-found on Cygwin/MSYS2 by converting the unique compiler PATH (COMPILER_UNIX_UNIQ_PATH / MSVS_PATH) to colon-separated POSIX with cygpath, so the VS bin directory is a usable PATH entry. BusyBox-w32 unchanged.

2.4.2-23

Fix host ./configure sed-not-found by appending /usr/bin:/bin to the unique compiler PATH (COMPILER_UNIX_UNIQ_PATH), which generates the host build launcher PATH. Cygwin/MSYS2 only; BusyBox-w32 unaffected.

2.4.2-22: Add /usr/bin:/bin to the Cygwin/MSYS2 compiler PATH

... so ./configure finds sed, expr, etc.

2.4.2-21: Fix ./configure missing sed/expr by normalizing the VsDevCmd PATH

+ Change autodetect_compiler_vsdev to build the cmd.exe PATH as a single
  all-Windows-format list (cygpath to POSIX, then back to Windows), because
  DKML_SYSTEM_PATH_WIN32 mixes Windows dirs (C:\...) with the POSIX /usr/bin.
  The 2.4.2-20 fix left it mixed: cmd.exe found reg.exe so the SDK was detected,
  but the MSYS2 /usr/bin did not survive the build's POSIX re-conversion, so the
  host `sh ./configure` could not find sed/expr ("cannot create .lineno; rerun
  with a POSIX shell").

2.4.2-20

bugfix: Windows SDK detection; use Windows-format PATH

2.4.2-19

do not use nonportable -t and -T for cp

2.4.2-18

Prepend DK_UNIX_ESSENTIALS/bin to compiler PATH

2.0.3-r2: Support FreeBSD SHA-256

Use [autodetect_system_binaries] so [awk]
is not from PATH.
Add test.