attached is a patch against the latest liboil to accept the doc USE flag
Created attachment 69256 [details, diff] liboil-0.3.2-doc_useflag.patch
the doc useflag also needs to introduce gtk-doc as a dependancy. Currently, the build fails with '/bin/sh: gtkdoc-scan: command not found' if gtk-doc is not installed. Also, patch probably needs to be updated and applied to all versions.
Ping... :)
This has already been fixed a while back.