Disable the deduction guide test I added in 309296 for the moment, while I figure out which compilers don't support deduction guides

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@309307 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/utilities/variant/variant.variant/variant.ctor/copy.pass.cpp

@@ -261,9 +261,13 @@ int main() {
   test_copy_ctor_valueless_by_exception();
   test_copy_ctor_sfinae();
   test_constexpr_copy_ctor_extension();
+#if 0
+// disable this for the moment; it fails on older compilers.
+//  Need to figure out which compilers will support it.
 { // This is the motivating example from P0739R0
   std::variant<int, double> v1(3);
   std::variant v2 = v1;
   (void) v2;
 }
+#endif
 }