ignore case for cwcheat

headers can have mixed case, which doesn't match common cheat files?
gpulib: fix frameskip cmd skipping
spu: check buffer state less often
spu: stop at address 0

or should we? (Music 2000)
spu: fix decode offset
gpulib: limit height
frontend: add layer height limit

otherwise some platforms may end up trying to set
resolutions with low height and fail
frontend: don't update during reset

otherwise update thread may collect input events that really
belong to UI. Another hack :(
gpulib: update after open
frontend: filter more unneeded files in browser
gpus: handle list underflows better
fully reinit drc on change
fix irq status

tested on real hardware
frontend: get rid of _FILE_OFFSET_BITS

pandora's zlib is too old to handle off_t with that define
frontend: minor menu refactoring
release r18