Support both old and new mkfs.f2fs

Easiest way I could find to determine if we have the old or the
new mkfs.f2fs version is to pipe the usage output to grep and
grep the output for "reserved" and redirect the output to a file.
If the file has any data in it, then we must have the old
mkfs.f2fs that uses -r.

Change-Id: I7f1ed88b577a3f9827a98f0868d8f82e4e4886ac
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index efaa460..669a9e9 100755
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -56,8 +56,8 @@
 	static string Get_Filename(const string& Path);                             // Trims the path off of a filename
 
 	static int Exec_Cmd(const string& cmd, string &result);                     //execute a command and return the result as a string by reference
-	static int Exec_Cmd(const string& cmd);                                     //execute a command
-	static int Wait_For_Child(pid_t pid, int *status, string Child_Name);       // Waits for pid to exit and checks exit status
+	static int Exec_Cmd(const string& cmd, bool Show_Errors = true);                   //execute a command, displays an error to the GUI if Show_Errors is true, Show_Errors is true by default
+	static int Wait_For_Child(pid_t pid, int *status, string Child_Name, bool Show_Errors = true); // Waits for pid to exit and checks exit status, displays an error to the GUI if Show_Errors is true which is the default
 	static int Wait_For_Child_Timeout(pid_t pid, int *status, const string& Child_Name, int timeout); // Waits for a pid to exit until the timeout is hit. If timeout is hit, kill the chilld.
 	static bool Path_Exists(string Path);                                       // Returns true if the path exists
 	static Archive_Type Get_File_Type(string fn);                               // Determines file type, 0 for unknown, 1 for gzip, 2 for OAES encrypted