Remove a source of nondeterminism from the LoopVectorizer.

This made us emit runtime checks in a random order. Hopefully bootstrap
miscompares will go away now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176775 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unneeded cast.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176776 91177308-0d34-0410-b5e6-96231b3b80d8