Parallel compilation of MultiWFN

[foxtran]

libreta has long compilation time (~40 min), so it would be nice to have parallelization of compilation process.

The following line should be updated:

homebrew-multiwfn/multiwfn.rb

Line 24 in c700ada

system "cmake", "--build", "build"

[kjelljorner]

Homebrew is supposed to handle that automatically based on the available CPUs on your system. What is the output log of a build with --verbose for you? On my system with 8 cores, I get -j8 for the MAKEFLAGS. I'm not aware of any way to do this is a more portable way, as it seems to be the standard way in homebrew-core for CMake builds.

...
==> ENV
HOMEBREW_CC: gcc-13
HOMEBREW_CXX: g++-13
MAKEFLAGS: -j8
...

To reduce time for the end user, it is probably better to build Homebrew "bottles" on GitHub Actions like here, but I don't have the bandwidth to set it up at the moment.