Fixed C++11 standard library error message

When including glm/gtx/hash.hpp before any other glm header files, the
error "GLM_GTX_hash requires C++11 standard library support" is thrown
because GLM_HAS_CXX11_STL is not yet defined.

glm/gtx/hash.hpp

@@ -41,10 +41,6 @@
 
 #pragma once
 
-#if !GLM_HAS_CXX11_STL
-#	error "GLM_GTX_hash requires C++11 standard library support"
-#endif
-
 #include <functional>
 
 #include "../vec2.hpp"
@@ -67,6 +63,10 @@
 #include "../mat4x3.hpp"
 #include "../mat4x4.hpp"
 
+#if !GLM_HAS_CXX11_STL
+#	error "GLM_GTX_hash requires C++11 standard library support"
+#endif
+
 namespace std
 {
 	template <typename T, glm::precision P>