xorg: Bump xcb-proto & libxcb version to 1.10

These have to be bumped together as new libxcb requires new xcb-proto, and
old libxcb doesn't build with new xcb-proto.

[Peter: fixup xcb-proto.pc instead of playing tricks with --define-variable]
Signed-off-by: Bernd Kuhls <berndkuhls@hotmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>