This patch adds support for the vector quadword add/sub instructions introduced

in POWER8.

These are the Clang-related changes for http://reviews.llvm.org/D9081

vadduqm
vaddeuqm
vaddcuq
vaddecuq
vsubuqm
vsubeuqm
vsubcuq
vsubecuq
All builtins are added in altivec.h, and guarded with the POWER8_VECTOR and
powerpc64 macros.



http://reviews.llvm.org/D9903

llvm-svn: 238145