mu4e recipe fails on FreeBSD

[arafel]

Hi

The mu4e recipe will fails to build on FreeBSD because it invokes plain make, which in this situation isn't GNU make. There are things in the Makefile specific to GNU make, so the build fails.

I'm using the mu4e recipe via straight, and I think it gets the recipe from this repo (apologies if not). I'm not great with elisp, and I haven't quite been able to work how to make the changes needed - essentially, for system-type equal to "berkeley-unix" it should use "gmake", else "make".

(Alternatively, run autogen.sh and then "meson compile -C build", "meson install -C build", which hides the make tool variance.)

Thanks
Paul