i3bar: Fix pixel offset calculation in dual-head

When running i3bar on a dual-head display with workspaces enabled in i3bar's
config, the second monitor wouldn't use a correct x position offset and
would draw its label too close to the screen's edge.  In comparison to the
first monitor, this is inconsistent because that starts with a pixel offset
of 1.

i3bar/src/xcb.c

@@ -1715,7 +1715,7 @@ void draw_bars(bool unhide) {
             unhide = true;
         }
 
-        i = 0;
+        i = 1;
     }
 
     if (!mod_pressed) {