Add myself to AUTHORS

I was looking around for changes that I could do. This what I came up with.
Seems boring, but nothing better came up this time.

Signed-off-by: Uli Schlachter <psychon@znc.in>
[ickle: Apologies for not doing it on your behalf.]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

AUTHORS

@@ -82,6 +82,7 @@ Calum Robinson <calumr@mac.com> Quartz backend
 Pavel Roskin <proski@gnu.org> Several cleanups to eliminate warnings
 Tim Rowley <tim.rowley@gmail.com> Quartz/ATSUI fixes, X server workarounds, win32 glyph path support, test case to expose gradient regression
 Soeren Sandmann <sandmann@daimi.au.dk> Lots of MMX love for pixman compositing
+Uli Schlachter <psychon@znc.in> Some more XCB fixes
 Torsten Schönfeld <kaffeetisch@gmx.de> Build fixes
 Jamey Sharp <jamey@minilop.net> Surface/font backend virtualization, XCB backend
 Jason Dorje Short <jdorje@users.sf.net> Build fixes and bug fixes