MFC r269948:

Supplement r259111 by also using correct casts in gcc's emmintrin.h for
the first argument of the following builtin function:

* __builtin_ia32_psrlqi128() takes __v2di instead of __v4si

This should fix the following errors when building the graphics/webp
port with base gcc:

lossless_sse2.c:403: error: incompatible type for argument 1 of '__builtin_ia32_psrlqi128'
lossless_sse2.c:404: error: incompatible type for argument 1 of '__builtin_ia32_psrlqi128'

Reported by:	Jos Chrispijn <ports@webrz.net>
MFC r269954:

Stop telling people to directly report llvm or clang bugs upstream,
point them to the FreeBSD bug tracker instead, since we use our own
patches.