If we receive unsupported event closing connection triggers valgrind
error.

==12017== Conditional jump or move depends on uninitialised value(s)
==12017==    at 0x487D454: _XFreeDisplayStructure (OpenDis.c:607)
==12017==    by 0x486857B: XCloseDisplay (ClDisplay.c:72)
*snip*
==12017==  Uninitialised value was created by a heap allocation
==12017==    at 0x4834C48: malloc (vg_replace_malloc.c:236)
==12017==    by 0x4894147: _XEnq (XlibInt.c:877)
==12017==    by 0x4891BF3: handle_response (xcb_io.c:335)
==12017==    by 0x4892263: _XReply (xcb_io.c:626)
*snip*

Problem is that XFreeDisplaySturture is checking for qelt->event.type ==
GenericEvent while _XUnknownWireEvent doesn't store the type.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Pauli Nieminen <ext-pauli.nieminen@nokia.com>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>