[libc++] Make sure we only consider _GNUC_VER_NEW when the compiler is GCC

When the compiler is Clang, _GNUC_VER_NEW is 0, which messes up the logic.

diff --git a/libcxx/include/variant b/libcxx/include/variant
index 5ea2cbd..33d5dc7 100644 (file)
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -230,7 +230,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 // TODO: GCC 5 lies about its support for C++17 (it says it supports it but it
 //       really doesn't). That breaks variant, which uses some C++17 features.
 //       Remove this once we drop support for GCC 5.
-#if _LIBCPP_STD_VER > 14 && !(_GNUC_VER_NEW < 6000)
+#if _LIBCPP_STD_VER > 14 && !(defined(_LIBCPP_COMPILER_GCC) && _GNUC_VER_NEW < 6000)
 
 _LIBCPP_NORETURN
 inline _LIBCPP_INLINE_VISIBILITY