Use /twres instead of /res for theme resources

AOSP and other ROM trees now do a rm -rf of the res folder during
the ramdisk creation process that removes the TWRP resources.
Using /twres instead of /res works around this issue making TWRP
more compatible with AOSP and other build trees.

Change-Id: I0d4c7e06ca381ac5aa0069b6f2b8c47f7dec49e7

gui/action.cpp

@@ -496,7 +496,7 @@ int GUIAction::reload(std::string arg)
 	{
 		// Loading the custom theme failed - try loading the stock theme
 		LOGINFO("Attempting to reload stock theme...\n");
-		if (PageManager::ReloadPackage("TWRP", "/res/ui.xml"))
+		if (PageManager::ReloadPackage("TWRP", TWRES "ui.xml"))
 		{
 			LOGERR("Failed to load base packages.\n");
 			ret_val = 1;