getting GLEW to work on Wayland

GLEW fails to initialise because there is no GLX on wayland and the one provided by distros was built to use GLX instead of EGL. This PR ignores the GLEW_ERROR_NO_GLX_DISPLAY error and it is a temporary fix until this is fixed by GLEW upstream. See nigels-com/glew#172

src/video/SDLGLVisibleSurface.cc

@@ -84,7 +84,7 @@ SDLGLVisibleSurface::SDLGLVisibleSurface(
 
 	// Initialise GLEW library.
 	GLenum glew_error = glewInit();
-	if (glew_error != GLEW_OK) {
+	if (glew_error != GLEW_OK && glew_error != GLEW_ERROR_NO_GLX_DISPLAY) {
 		throw InitException(
 			"Failed to init GLEW: ",
 			reinterpret_cast<const char*>(