Build Release Binaries with openmp

[everythingfunctional]

Description

I don't know if there are downsides to doing so, but it would be nice if the default fpm could do parallel builds, as it would save me some time in my CI.

Possible Solution

Add the openmp meta package as a dependency in fpm's fpm.toml or modify the scripts compiling the binaries for the release to include the -fopenmp flag.

Additional Information

I've got some projects that are big enough they would really benefit from parallel builds.

[perazz]

I think it's a good idea to ship pre-built binaries with openmp support for parallel builds and I hoped it would be relatively straightforward to implement.

• We cannot use the openmp metapackage until fpm >=0.9.0 is used for bootstrapping
• There is a problem with the Ubuntu build, which causes a segfault when built with openmp:

https://github.com/perazz/fpm/actions/runs/6106695766/job/16572241595

This will need more debugging