Correct patch paths (remove contrib/llvm/)

The example in contrib/llvm/patches/README.TXT fails otherwise.

Sponsored by:	DARPA, AFRL
Add the fp{get,set}{mask,round} functions to the public symbols in the map.
These are only exported for armv6hf as the soft-float ABIs have these in
the softfloat Symbol.map file.
vt_vga: vd_setpixel_t and vd_drawrect_t are noop in text mode

MFC after:	3 days