Fixed an issue when compiling Doom and not prey.

neo/renderer/Material.cpp

@@ -1906,11 +1906,13 @@ idMaterial::GetGlowImage
 ===================
 */
 idImage* idMaterial::GetGlowImage(void) const {
+#ifdef PREY
 	for (int i = 0; i < numStages; i++) {
 		if ((stages[i].lighting == SL_GLOWMAP  || stages[i].isGlow) && stages[i].texture.image) {
 			return stages[i].texture.image;
 		}
 	}
+#endif
 	return NULL;
 }