Silencing an MSVC C4334 warning ('<<' : result of 32-bit shift implicitly converted to 64 bits (was 64-bit shift intended?)). NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216902 91177308-0d34-0410-b5e6-96231b3b80d8