bug#57015: 29.0.50; macOS: libgccjit was not found: Homebrew libgccjit 12.1.0

[Dario Gjorgjevski <dario.gjorgjevski@gmail.com>]

Naofumi Yasufuku <naofumi@yasufuku.dev> writes:

> './configure --with-native-compilation' fails if Homebrew libgccjit is
> updated to 12.1.0.  Attached configure.ac patch fixes this issue.
> I think the same patch should be applied to emacs-28 branch.

As an alternative to your patch and the general approach based on
running `grep` over the output of `brew ls`, one can also use

    % brew ruby -e 'puts "#{:libgccjit.f.lib}/gcc/#{:gcc.f.any_installed_version.major}"'
    /usr/local/opt/libgccjit/lib/gcc/12

for MAC_LIBS, and

    % brew ruby -e 'puts :libgccjit.f.include'
    /usr/local/opt/libgccjit/include

for MAC_CFLAGS.  This will work with both versions 11 and 12 of
Homebrew's `libgccjit`.

Best regards,
Dario