layout.arrange: delay a call per screen

This is a followup / fix for 7410646, which did not handle multiple
arrange calls to different screens per main lopp.

lib/awful/layout/init.lua.in

@@ -42,6 +42,8 @@ layout.layouts = {
 -- This is a special lock used by the arrange function.
 -- This avoids recurring call by emitted signals.
 local arrange_lock = false
+-- Delay one arrange call per screen.
+local delayed_arrange = {}
 
 --- Get the current layout.
 -- @param screen The screen number.
@@ -95,10 +97,13 @@ end
 --- Arrange a screen using its current layout.
 -- @param screen The screen to arrange.
 function layout.arrange(screen)
-    if arrange_lock then return end
-    arrange_lock = true
+    if delayed_arrange[screen] then return end
+    delayed_arrange[screen] = true
 
     timer.delayed_call(function()
+        if arrange_lock then return end
+        arrange_lock = true
+
         local p = {}
         p.workarea = capi.screen[screen].workarea
         -- Handle padding
@@ -116,6 +121,7 @@ function layout.arrange(screen)
         capi.screen[screen]:emit_signal("arrange")
 
         arrange_lock = false
+        delayed_arrange[screen] = nil
     end)
 end