Replace `RL_FREE` with `RAYGUI_FREE` (#479)

src/raygui.h

@@ -4443,8 +4443,8 @@ void GuiLoadStyleDefault(void)
     {
         // Unload previous font texture
         UnloadTexture(guiFont.texture);
-        RL_FREE(guiFont.recs);
-        RL_FREE(guiFont.glyphs);
+        RAYGUI_FREE(guiFont.recs);
+        RAYGUI_FREE(guiFont.glyphs);
         guiFont.recs = NULL;
         guiFont.glyphs = NULL;