Fix compilation on Apple silicon

[flatmapthatshit]

Builds are currently failing on M1 Mac due to Homebrew using a different path on M1 Macs (see Render96#47 for further details).
All credits for the fix goes to @halpz (original PR: Render96#48).

Additionally, while the Wiki often encourages parallel builds (e.g., with make -j4), tools/Makefile is not currently safe for parallel builds as it doesn't currently account for dependencies between programs.

E.g.:

• tabledesign → audiofile
• skyconv → n64graphics

More often than not, trying to compile tools with gmake OSX_BUILD=1 -j4 will fail due to tabledesign finishing to compile before audiofile and then failing to link.

While this would ideally be solved by introducing separate rules per program accounting for dependencies, for now I'm forcing j1 for tools.

[fgsfdsfgs]

Interesting. I can't test whether this breaks builds on other Macs since I don't have any, but it doesn't look like it should, so merging. Thanks. Pinging #452 in case anyone's watching that.