Implement soft-patching for libretro core

[fox140cv]

Is it possible to add this function again ?, shortly after Byuu left the project the soft patch stopped working in the libretro core.

[Screwtapello]

I don't know about the various bsnes-based cores libretro has used in the past, but as of right now the current libretro core has a commented-out call to apply a soft-patch:

bsnes/bsnes/target-libretro/program.cpp

Line 483 in 6b38388

//superFamicom.patched = applyPatchIPS(rom, location);

The equivalent code in the standalone bsnes UI tries soft-patching both IPS and BPS:

bsnes/bsnes/target-bsnes/program/game.cpp

Lines 127 to 128 in 0ab0ab6

	if(!superFamicom.patched) superFamicom.patched = applyPatchIPS(rom, location);
	if(!superFamicom.patched) superFamicom.patched = applyPatchBPS(rom, location);

Uncommenting the call in the libretro target won't work, since the applyPatchIPS function only exists in the standalone UI right now - I assume that commented-out call is leftover from when the libretro core was created. It may be as easy as copying the applyPatchIPS and applyPatchBPS functions across and calling them in the right place.. or maybe it's more complex than that. Either way, this should probably be done sooner or later.