[Xcb] quick ABI/API-compat audit

[Mark Kettenis]

> From: Christian Linhart <chris at DemoRecorder.com>
> Date: Mon, 1 Feb 2016 09:03:16 +0100
> 
> Hi,
> 
> I have made a quick ABI/API audit by diffing the headerfiles, to see
> where we are with respect to a new release.
> 
> Here are the major issues (blockers) that I have found:
> =======================================================
> 
> All of the major issues are in the XPRINT-extension.  Is XPRINT
> still in use somewhere?  If its not in use anywhere we may get away
> with releasing a changes ABI/API for the XCB impl of XPRINT.

XPRINT is dead.  It has been removed from the X.Org xserver reference
implementation, and the git repo for the split-off sources has not
seen any activity since 2009.  This repository is clearly marked as
deprecated.

Probably good enough to just bump the shared library major for this.

We do seem to ship libxcb-xprint shared libraries on OpenBSD, and we
did already bump the shared library major number twice over the last
couple of years.