Print vectorization analysis when loop hint is specified.

Print vectorization analysis when loop hint is specified.

This patch and a relatec clang patch solve the problem of having to explicitly enable analysis when specifying a loop hint pragma to get the diagnostics. Passing AlwasyPrint as the pass name (see below) causes the front-end to print the diagnostic if the user has specified '-Rpass-analysis' without an '=<target-pass>’. Users of loop hints can pass that compiler option without having to specify the pass and they will get diagnostics for only those loops with loop hints.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244555 91177308-0d34-0410-b5e6-96231b3b80d8