patch 8.0.1713: terminal debugger doesn't handle arguments

Problem:    Terminal debugger doesn't handle arguments.
Solution:   Use <f-args> and pass all the arguments to gdb, e.g. the core file
            or process number. (suggested by Christian Brabandt) Disallow
            starting the debugger twice.

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1713,
 /**/
     1712,
 /**/