Clear the relative directory before passing on to twrpTar with the static du object. Otherwise we will not backup /system/media etc

Change-Id: Ib62af6ad8596aa18bf48cb750e2ecf442dadc627
diff --git a/twrpDU.hpp b/twrpDU.hpp
index 04527cd..dac15f1 100644
--- a/twrpDU.hpp
+++ b/twrpDU.hpp
@@ -40,8 +40,9 @@
 	uint64_t Get_Folder_Size(const string& Path); // Gets the folder's size using stat
 	void add_absolute_dir(string Path);
 	void add_relative_dir(string Path);
-	bool check_skip_dirs(string& dir);            // Checks a list of directories to see if we should skip it
+	bool check_skip_dirs(string& dir);
 	vector<string> get_absolute_dirs(void);
+	void clear_relative_dir(string dir);
 private:
 	vector<string> absolutedir;
 	vector<string> relativedir;