[libcxx] Improve tests to use the UNSUPPORTED lit directive

Quite a few libcxx tests seem to follow the format:
 #if _LIBCPP_STD_VER > X
   // Do test.
 #else
   // Empty test.
 #endif
We should instead use the UNSUPPORTED lit directive to exclude the test on
earlier C++ standards. This gives us a more accurate number of test passes
for those standards and avoids unnecessary conflicts with other lit
directives on the same tests.

Reviewers: bcraig, ericwf, mclow.lists

Differential revision: http://reviews.llvm.org/D20730

llvm-svn: 271108
diff --git a/libcxx/test/std/utilities/function.objects/comparisons/transparent.pass.cpp b/libcxx/test/std/utilities/function.objects/comparisons/transparent.pass.cpp
index 41ce4bc..f353fe7 100644
--- a/libcxx/test/std/utilities/function.objects/comparisons/transparent.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/comparisons/transparent.pass.cpp
@@ -7,6 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: c++98, c++03, c++11
 #include <functional>
 #include <string>
 
@@ -22,9 +23,8 @@
 };
 
 
-int main () {
-#if _LIBCPP_STD_VER > 11
-
+int main ()
+{
     static_assert ( !is_transparent<std::less<int>>::value, "" );
     static_assert ( !is_transparent<std::less<std::string>>::value, "" );
     static_assert (  is_transparent<std::less<void>>::value, "" );
@@ -55,7 +55,5 @@
     static_assert (  is_transparent<std::greater_equal<void>>::value, "" );
     static_assert (  is_transparent<std::greater_equal<>>::value, "" );
 
-#endif
-
     return 0;
-    }
+}