added flags GLM_CONSTEXPR_CXX14 and GLM_CONSTEXPR_CTOR_CXX14

glm/detail/setup.hpp

@@ -742,6 +742,14 @@
 #	define GLM_RELAXED_CONSTEXPR const
 #endif
 
+#if GLM_LANG >= GLM_LANG_CXX14
+#	define GLM_CONSTEXPR_CXX14 GLM_CONSTEXPR
+#	define GLM_CONSTEXPR_CTOR_CXX14 GLM_CONSTEXPR_CTOR
+#else
+#	define GLM_CONSTEXPR_CXX14
+#	define GLM_CONSTEXPR_CTOR_CXX14
+#endif
+
 #if GLM_ARCH == GLM_ARCH_PURE
 #	define GLM_CONSTEXPR_SIMD GLM_CONSTEXPR_CTOR
 #else