loaders: PNM: Optimize Save()
loaders: PNM: Optimize Save()

This adds custom function to write ASCII byte into a file which is more
than five times faster than printf("%u", byte).

Signed-off-by: Cyril Hrubis <b1e90efd3b808b8e0bcf2a9a55fd8b9a779bfd81@ucw.cz>

gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim