sdl2: refactor image channel code, more palette function coverage

SDL: readjust/add more scancodes

SDL: scancodes: place command & period properly (thanks uramekus)

sdl2: add SDL_PIXELFORMAT_ABGR8888

sdl2: add SDL_LockTexture and SDL_UnlockTexture

parg: fix a few warnings

npe: add getopt and getopt_long (based on parg)

npe: add strerror_r

pthread: fix const/pointer mess

npe: add cbrtf

npe: add hypotf

npe: add ldexpf

sigaction: do not crash

npe: sigemptyset and more signal stuff

npe: PRI* do not have %

npe: add div

npe: add fmax

npe: add acosh and log1p

forgot to add the file

define PRIuPTR