Don't set getdir_click unless we've requested it

This allowed eg. throwing the iron ball anywhere on the map,
by first throwing something else, using the "simulated mouse click"
to select any map location, and then throwing the iron ball and
also using the mouse click feature to select any location.

Currently the only function that actually uses the simulated
mouse click feature is #therecmdmenu

src/cmd.c

@@ -5344,7 +5344,8 @@ getdir(const char *s)
                 break;
             }
         }
-        iflags.getdir_click = mod;
+        if (iflags.getdir_click)
+            iflags.getdir_click = mod;
         return (pos >= 0);
     } else if (!(is_mov = movecmd(dirsym, MV_ANY)) && !u.dz) {
         boolean did_help = FALSE, help_requested;