[Cairo] [patch] implement push/pull on xc surfaces

[Carl Worth]

On Sep 6, Eric Christopherson wrote:
 > After updating and recompiling, I still only get BadValue errors (failed
 > X_CreatePixmap request) when I try to run the demos.

Here's the traditional recipe for debugging X protocol errors:

1) Add the following call to your program, just after a successful
   XOpenDisplay, then recompile:

	XSynchronize (dpy, 1);

2) Run your program in a debugger:

	gdb a.out

3) Set a breakpoint at the _XError function:

	break _XError

4) Begin execution, (it will stop at the protocol error):

	run

5) Examine the stack to find the bug:

	info stack

If you do that and can't make sense of the stack or find the bug
yourself, feel free to send me the stack dump and I'll take a look.

Thanks,

-Carl