uicb_tag_view not working correctly with null argument

uicb_tag_view(...) hasn't been working correctly since tag_view(...)
came into existence. The problem is that saveawesomeprops(...),
arrange(...) and ewmh_update_net_current_desktop(...) need to be called
for a NULL argument as well, but these were moved to tag_view(...).

We can either add them back albeit only for the arg=NULL case, or move
these calls back into uicb_tag_view(...) and copy them over to
ewmh_process_client_message(...) and to all possible future users of
tag_view(...). The attached patch does the former.

tag.c

@@ -335,8 +335,13 @@ uicb_tag_view(int screen, char *arg)
     if(arg)
 	tag_view(screen, atoi(arg) - 1);
     else
+    {
         for(tag = globalconf.screens[screen].tags; tag; tag = tag->next)
             tag->selected = True;
+        saveawesomeprops(screen);
+        arrange(screen);
+        ewmh_update_net_current_desktop(get_phys_screen(screen));
+    }
 }
 
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