R600/SI: Use bcnt instruction for ctpop

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210567 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Implement i64 ctpop

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210568 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Use BCNT_INT for evergreen

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210569 91177308-0d34-0410-b5e6-96231b3b80d8