X11: fix kded xcb resource leak
This fixes commit 579358f5
XOpenDisplay() internally calls xcb_connect(), creating a new XCB client connection. This means that on every KScreen configuration change event the kded5 process creates a new connection until XCB runs into the hard limit of 256 of clients, leading to the dreaded "Maximum number of clients reached" error.
Re-use the display from QX11Info instead of calling XOpenDisplay().
Edited by Stefan Becker