[libcxx] Add appropriate 'REQUIRE' directives to tests that require en_US.UTF-8.

Reviewers: mclow.lists, hans

Subscribers: bcraig, cfe-commits

Differential Revision: http://reviews.llvm.org/D16406

llvm-svn: 258403
diff --git a/libcxx/test/std/re/re.traits/default.pass.cpp b/libcxx/test/std/re/re.traits/default.pass.cpp
index c9a97e0..defadd9 100644
--- a/libcxx/test/std/re/re.traits/default.pass.cpp
+++ b/libcxx/test/std/re/re.traits/default.pass.cpp
@@ -8,6 +8,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <regex>
 
 // template <class charT> struct regex_traits;