PKG: differentiate uClibc & musl PGO data

[Apaczer]

• split uClibc & musl PGO=APPLY pre build cmds
• add musl PGO data
  • libretro-mednafen-wswan (musl)
  • libretro-gpsp (musl->uclibc_copy)
  • libretro-pcsx (musl->uclibc_copy)
  • libretro-snes9x2002 (musl->uclibc_copy)

Generally we shouldl not use the same profiling data for both libs, even some minor miss code coverage can result in worse optimization, not to mention difference in memory allocation and threading which IMO may obscure profiling. The difference is much noticable in libretro-mednafen-wswan in favor of using unique *.gcda.
That being said there still may be some perf. benefit over not using PGO at all, so for missing musl gcov data let us for now copy over from uclibc profiler.

[Apaczer]

via GCC man 10.1:

You should compile your code without optimization if you plan to use gcov because the optimization, by combining some lines of code into one function, may not give you as much information as you need to look for ‘hot spots’ where the code is using a great deal of computer time

so it may be worth doing next time profiling with -O0