Update xml-xcb.txt to include new <bit> expression.
Update xml-xcb.txt to include new <bit> expression.

nbaum/xcb-proto,nbaum/xcb-proto,OpenInkpot-archive/iplinux-xcb-proto,stapelberg/xcb-proto,stapelberg/xcb-proto,OpenInkpot-archive/iplinux-xcb-proto