xkb: Guard against SIGIO updates during PointerKeys.

In theory, an event coming in during GPE could reset our lastSlave, leading
to rather interesting events lateron.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Simon Thum <simon.thum@gmx.de>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>

xkb/ddxDevBtn.c

@@ -64,11 +64,12 @@ XkbDDXFakeDeviceButton(DeviceIntPtr dev,Bool press,int button)
         return;
 
     events = InitEventList(GetMaximumEventsNum());
+    OsBlockSignals();
     nevents = GetPointerEvents(events, ptr,
                                press ? ButtonPress : ButtonRelease, button,
                                0 /* flags */, 0 /* first */,
                                0 /* num_val */, NULL);
-
+    OsReleaseSignals();
 
     for (i = 0; i < nevents; i++)
         mieqProcessDeviceEvent(ptr, (InternalEvent*)events[i].event, NULL);