Use BitVector instead of int in R600 SIISelLowering.
int may not have enough bits in it, which was detected by UBSan
bootstrap (it reported left shift by a too large constant).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216579 91177308-0d34-0410-b5e6-96231b3b80d8