Change array to plain member

* Some clang versions seem to complain about the storage for this being missing
  even if it's constexpr, since it's not important we make it a plain member.

util/test/demos/gl/gl_test.h

@@ -79,7 +79,7 @@ struct OpenGLGraphicsTest : public GraphicsTest
   GLuint DefaultTriProgram;
   GLuint swapBlitFBO;
 
-  static constexpr GLfloat DefaultClearCol[] = {0.2f, 0.2f, 0.2f, 1.0f};
+  GLfloat DefaultClearCol[4] = {0.2f, 0.2f, 0.2f, 1.0f};
 
   GraphicsWindow *mainWindow = NULL;
   void *mainContext = NULL;