XCB: Append 0-character to atom name string.

The below loop needs 2 consecutive 0-characters to terminate
properly.

Change-Id: I73e56cadbcd2515d5b0f1b4907316a27a6bbaf0e
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

src/plugins/platforms/xcb/qxcbconnection.cpp

@@ -1397,7 +1397,7 @@ static const char * xcb_atomnames = {
 #if XCB_USE_MAEMO_WINDOW_PROPERTIES
     "_MEEGOTOUCH_ORIENTATION_ANGLE\0"
 #endif
-    "_XSETTINGS_SETTINGS"
+    "_XSETTINGS_SETTINGS\0" // \0\0 terminates loop.
 };
 
 xcb_atom_t QXcbConnection::atom(QXcbAtom::Atom atom)