Add SPARC v9 support for select on 64-bit compares.

This requires v9 cmov instructions using the %xcc flags instead of the
%icc flags.

Still missing:
- Select floats on %xcc flags.
- Select i64 on %fcc flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178737 91177308-0d34-0410-b5e6-96231b3b80d8