quartz menu: add a hack for application name

Add a private hack to allow the insertion of the name of the application
into the label of menu items.

If it appears in the label of any menu item, the string
"`gtk-private-appname`" will be replaced with the name of the
application.

We will use this for the "Hide myapp", "Quit myapp" and "About myapp"
labels typically found on Mac OS programs.

gtk/gtkapplication-quartz-menu.c

@@ -433,8 +433,13 @@ tracker_item_changed (GObject    *object,
 {
   NSString *label = [NSString stringWithUTF8String:gtk_menu_tracker_item_get_label (trackerItem) ? : ""];
   NSMutableString *title = [NSMutableString stringWithCapacity:[label length]];
+  NSRange range;
   int i;
 
+  range = [label rangeOfString:@"`gtk-private-appname`"];
+  if (range.location != NSNotFound)
+    label = [label stringByReplacingCharactersInRange:range withString:[[NSProcessInfo processInfo] processName]];
+
   for (i = 0; i < [label length]; i++)
     {
       unichar c = [label characterAtIndex:i];