Portability issues (on PS3)

Remaining portability issues (this is explicitly for PS3 now, but other platforms will have even more stripped toolchains so let's please take care of all this 'platform' code in FUSE and make it resemble something far more portable than what it is right now) -

Command line : error: L0039: reference to undefined symbol .getopt_long' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(settings.o)" Command line : error: L0039: reference to undefined symbol.getcwd' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(filesel.o)"
Command line : error: L0039: reference to undefined symbol .chdir' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(filesel.o)" Command line : error: L0039: reference to undefined symbol.isatty' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(commandl.o)"
fixme:process:GetProcessWorkingSetSize (0xffffffff,0x33fbdc,0x33fbd8): stub
settings.c(1) : error: L0039: reference to undefined symbol .getopt_long' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(settings.o)" settings.c(1) : error: L0039: reference to undefined symbol.getopt_long' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(settings.o)"
filesel.c(1) : error: L0039: reference to undefined symbol .getcwd' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(filesel.o)" filesel.c(1) : error: L0039: reference to undefined symbol.chdir' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(filesel.o)"
commandl.c(1) : error: L0039: reference to undefined symbol `.isatty' in file "Z:\home\squarepusher\libretro-super\retroarch\libretro_ps3.a(commandl.o)"

Libretro cores are really opposed to this kind of non-decoupled, kitchensink-like codebase where it tries to do a lot of internals like file and disk I/O on its own. As you can see, it introduces lots of portability hazards.

Not sure what the best way to go about it would be. Maybe we need some kind of libretro-common-like wrapper for certain emulators that need to do file I/O, signals, TTY, and/or other low-level things like that, except in this libretro-common-like wrapper we then make sure it works for every target we support.

Review the PS3 linker output alongside settings.c, filesel.c, and commandl.c, then identify how platform code handles getopt_long, getcwd, chdir, and isatty. Done means the affected supported-target builds link without these undefined-symbol errors and the portability scope is resolved.