wibox.wibox.systray: Allow multiple systrays

This has to be removed because it breaks the fallback to the default config if
the first config already managed to create a systray widget. This doesn't mean
that it is suddenly possible to have the systray visible in more than one place,
it just means that awesome will no longer complain about this.

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/wibox/widget/systray.lua.in

@@ -15,7 +15,6 @@ local abs = math.abs
 --- wibox.widget.systray
 local systray = { mt = {} }
 
-local created_systray = false
 local horizontal = true
 local base_size = nil
 
@@ -62,11 +61,6 @@ end
 local function new()
     local ret = wbase.make_widget()
 
-    if created_systray then
-        error("More than one systray created!")
-    end
-    created_systray = true
-
     ret.fit = systray.fit
     ret.draw = systray.draw
     ret.set_base_size = function(_, size) base_size = size end