The built-in make is a POSIX make tool, which doesn't support
GNU make features.
As we do have GNU make, insert that as "make.exe" in the busybox
directory. Don't do that in the main llvm-mingw bin directory,
which can be used with other environments (e.g. msys2), where the
native make is to be preferred.
This allows running the built busybox on older versions of
Windows that don't support the utf8 manifest. (The utf8 manifest
is supported since Windows 10 update 1903.)
When building with mingw32-make, it prefers executing commands
through "sh.exe" if it is available.
When busybox sh.exe executes "ar", it prefers executing its own
internal tool over a potential external tool found in $PATH.
(This can be avoided by setting 'export BB_OVERRIDE_APPLETS="ar"',
but as this build of busybox is expected to be used with llvm-mingw,
disable the built-in "ar" tool outright.)
Martin Storsjö