Summary:
This patch adds a "REQUIRES-ANY" feature test that is disjunctive. This marks a test as `UNSUPPORTED` if none of the specified features are available.
Libc++ has the need to write feature test such as `// REQUIRES-ANY: c++98, c++03` when testing of behavior that is specific to older dialects but has since changed.
Reviewers: rnk, ddunbar
Subscribers: ddunbar, probinson, llvm-commits, cfe-commits
Differential Revision: http://reviews.llvm.org/D20757
llvm-svn: 271468