Patch follows.
Created attachment 212361 [details, diff] libxcb-1.4-r1.diff
Comment on attachment 212361 [details, diff] libxcb-1.4-r1.diff NAK on this patch. We just need to add htmldir to the eclass like we did for docdir. @herd, we should also fix the proto packages to use standard automake docdir like Tomáš recently did for libXrender. Thanks
Hm this stuff should be really fixed in the tree nowdays with xorg-2 eclass Reopen if i am wrong.