Add option to uninstall TWRP app from /system

Change-Id: Ibe372a372333c357810be2afcb3796723ca370cb
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index a892e75..8cea321 100755
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -106,6 +106,7 @@
 	static int stream_adb_backup(string &Restore_Name); // Tell ADB Backup to Stream to TWRP from GUI selection
 	static std::string get_cache_dir(); // return the cache partition existence
 	static void check_selinux_support(); // print whether selinux support is enabled to console
+	static bool Is_TWRP_App_In_System(); // Check if the TWRP app is installed in the system partition
 
 private:
 	static void Copy_Log(string Source, string Destination);