This patch adds ABI support for v1i128 data type.

It adds v1i128 to the appropriate register classes and checks parameter passing
and return values.

This is related to http://reviews.llvm.org/D9081, which will add instructions
that exploit the v1i128 datatype.

Phabricator review: http://reviews.llvm.org/D9475

llvm-svn: 236503