Fix broken shader that prevents game start

Author: Antoine Fontaine

src/engine/renderer/glsl_source/generic_fp.glsl

@@ -77,13 +77,13 @@ void	main()
 #endif
 
 	color *= var_Color;
-	
+
 	SHADER_PROFILER_SET( color )
 
 	outputColor = color;
 
 // Debugging.
-if defined(USE_MATERIAL_SYSTEM) && defined(r_showGlobalMaterials)
+#if defined(USE_MATERIAL_SYSTEM) && defined(r_showGlobalMaterials)
 	outputColor.rgb = u_MaterialColour;
 #endif
 }