xcb: Be able to compile without xlib support

xcb: Be able to compile without xlib support

Use XCB types for events instead of indirectly depending
on Xlib includes because of the GLX includes. Manually verified
the right values.

ButtonPressMask			(1L<<2)
XCB_EVENT_MASK_BUTTON_PRESS = 4,

define ButtonReleaseMask		(1L<<3)
XCB_EVENT_MASK_BUTTON_RELEASE = 8,

ButtonMotionMask		(1L<<13)
XCB_EVENT_MASK_BUTTON_MOTION = 8192,

EnterWindowMask			(1L<<4)
XCB_EVENT_MASK_ENTER_WINDOW = 16,

LeaveWindowMask			(1L<<5)
XCB_EVENT_MASK_LEAVE_WINDOW = 32,

PointerMotionMask		(1L<<6)
XCB_EVENT_MASK_POINTER_MOTION = 64,

GrabModeAsync		1
XCB_GRAB_MODE_ASYNC = 1

Change-Id: I1fade68947b1e2f39ca3514573c10fae7ee2dfb1
Reviewed-on: http://codereview.qt.nokia.com/3664
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>