Add the following 64-bit vector integer arithmetic instructions added in POWER8:

vaddudm
vsubudm
vmulesw
vmulosw
vmuleuw
vmulouw
vmuluwm
vmaxsd
vmaxud
vminsd
vminud
vcmpequd
vcmpequd.
vcmpgtsd
vcmpgtsd.
vcmpgtud
vcmpgtud.
vrld
vsld
vsrd
vsrad

Phabricator review: http://reviews.llvm.org/D7959

llvm-svn: 231115