Rename the C function to create a SLPVectorizerPass to something sane and expose it in the header file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179272 91177308-0d34-0410-b5e6-96231b3b80d8
Add braces around || in && to pacify GCC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179275 91177308-0d34-0410-b5e6-96231b3b80d8