bug#55455: [macOS] Fix build when using brew's libgccjit

[John Buckley]

> Daniel Martin <mardani29@yahoo.es>

> I think this is a duplicate of bug#55173, which should be fixed already.
> Could you try to build Emacs with native compilation from the master branch?

Yes it is as confirmed by Robert. 

All is ok now on `master`. I've been on emacs-28 for a while now, probably time to move to master.

> Eli Zaretskii <eliz@gnu.org>

> By "now" do you mean in some recent enough version?  That is, older

> versions will still use the .so extension?

Older versions of gcc used the wrong dynamic library extension for libgccjit on macOS. Brew on X86_64 uses the latest version. However, brew on ARM64 is still using the .so version because it depends on an older fork of gcc. So both need to be supported.

> Shouldn't we try both extensions?

The fix in master does this correctly.

Thanks for the comments - all resolved now.

On Mon, 16 May 2022 at 17:23, Eli Zaretskii <eliz@gnu.org> wrote:

> From: John Buckley <nhoj.buckley@gmail.com>
> Date: Mon, 16 May 2022 12:38:14 +0100
>
> libgccjit installed via Homebrew now uses the correct .dylib dynamic library
> extension on macOS.

By "now" do you mean in some recent enough version?  That is, older
versions will still use the .so extension?

> This causes configure to fail because it is still
> using the .so extension.
>
> The attached patch fixes the libgccjit library extension in configure.ac

Shouldn't we try both extensions?

Thanks.