As it contains more than one package, the "Xorg" version was used, which is 7.7. For the exact versions see tcz/src/libxcb:
libpthread-stubs-0.3.tar.bz2 xcb-proto-1.8.tar.bz2 xcb-util-image-0.3.9.tar.bz2
libxcb-1.9.1.tar.bz2 xcb-util-0.3.9.tar.bz2 xcb-util-renderutil-0.3.8.tar.bz2