* Makefile: macOS Package Manager & Compiler detection
* Makefile: (Moderate) Build Speed improvements:
0) use gnu make "simply expanded" variable
1) use gnu make `shell` function instead of backticks
2) collectively these avoid multiple variable expansions per compiler call
3) should most significantly improve I/O bound platforms (e.g. MSYS2)
* Makefile: revert "Compiler Options" comment change
* Makefile: Move `PLATFORM_CFLAGS` to a less intrusive location
same idea as n64decomp/sm64's armips.cpp
you can generate the file by applying tools/util/audiofile_strip.patch and running tools/util/generate_audiofile_cpp.py on a full audiofile source package