Drive-by comment fix. This regalloc comment was not accurate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202432 91177308-0d34-0410-b5e6-96231b3b80d8
Provide a target override for the latest regalloc heuristic.

This is a temporary workaround for native arm linux builds:
PR18996: Changing regalloc order breaks "lencod" on native arm linux builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202433 91177308-0d34-0410-b5e6-96231b3b80d8