Implement N3421; comparison predicates<void>

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@187357 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/utilities/function.objects/arithmetic.operations/modulus.pass.cpp b/test/utilities/function.objects/arithmetic.operations/modulus.pass.cpp
index 542711f..421f945 100644
--- a/test/utilities/function.objects/arithmetic.operations/modulus.pass.cpp
+++ b/test/utilities/function.objects/arithmetic.operations/modulus.pass.cpp
@@ -21,4 +21,11 @@
     const F f = F();
     static_assert((std::is_base_of<std::binary_function<int, int, int>, F>::value), "");
     assert(f(36, 8) == 4);
+#if _LIBCPP_STD_VER > 11
+    typedef std::modulus<> F2;
+    const F2 f2 = F2();
+    assert(f2(36, 8) == 4);
+    assert(f2(36L, 8) == 4);
+    assert(f2(36, 8L) == 4);
+#endif
 }