Explicitly request unsigned enum types when desired

This fixes repeated -Wmicrosoft warnings when self-hosting clang on
Windows, and gets us real unsigned enum types with MSVC.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192228 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed