gtk-doc: add deps on docbook in Windows and OSX
gtk-doc: add deps on docbook in Windows and OSX

jackjansen/cerbero,nicolewu/cerbero,nirbheek/cerbero-old,GStreamer/cerbero,AlertMe/cerbero,flexVDI/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,superdump/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,ramaxlo/cerbero,ramaxlo/cerbero,OptoFidelity/cerbero,superdump/cerbero,centricular/cerbero,multipath-rtp/cerbero,nzjrs/cerbero,davibe/cerbero,cee1/cerbero-mac,centricular/cerbero,shoreflyer/cerbero,OptoFidelity/cerbero,nirbheek/cerbero,nirbheek/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,EricssonResearch/cerbero,ikonst/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero,nzjrs/cerbero,jackjansen/cerbero,nzjrs/cerbero,jackjansen/cerbero-2013,superdump/cerbero,ikonst/cerbero,ford-prefect/cerbero,fluendo/cerbero,nzjrs/cerbero,brion/cerbero,fluendo/cerbero,shoreflyer/cerbero,ylatuya/cerbero,ylatuya/cerbero,nicolewu/cerbero,OptoFidelity/cerbero,ramaxlo/cerbero,atsushieno/cerbero,atsushieno/cerbero,jackjansen/cerbero-2013,centricular/cerbero,multipath-rtp/cerbero,sdroege/cerbero,nzjrs/cerbero,jackjansen/cerbero-2013,cee1/cerbero-mac,ikonst/cerbero,davibe/cerbero,justinjoy/cerbero,ramaxlo/cerbero,AlertMe/cerbero,multipath-rtp/cerbero,jackjansen/cerbero,brion/cerbero,nirbheek/cerbero,nirbheek/cerbero,fluendo/cerbero,ikonst/cerbero,lubosz/cerbero,BigBrother-International/gst-cerbero,flexVDI/cerbero,fluendo/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,BigBrother-International/gst-cerbero,justinjoy/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,justinjoy/cerbero,brion/cerbero,OptoFidelity/cerbero,nirbheek/cerbero-old,nirbheek/cerbero-old,atsushieno/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,centricular/cerbero,shoreflyer/cerbero,ford-prefect/cerbero,EricssonResearch/cerbero,cee1/cerbero-mac,GStreamer/cerbero,cee1/cerbero-mac,brion/cerbero,AlertMe/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,GStreamer/cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,flexVDI/cerbero,BigBrother-International/gst-cerbero,freedesktop-unofficial-mirror/gstreamer__cerbero,centricular/cerbero,AlertMe/cerbero,sdroege/cerbero,multipath-rtp/cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,ford-prefect/cerbero,multipath-rtp/cerbero,davibe/cerbero,EricssonResearch/cerbero,EricssonResearch/cerbero,lubosz/cerbero,BigBrother-International/gst-cerbero,nirbheek/cerbero-old,GStreamer/cerbero,lubosz/cerbero,AlertMe/cerbero,lubosz/cerbero,jackjansen/cerbero,sdroege/cerbero,ylatuya/cerbero,atsushieno/cerbero,ramaxlo/cerbero,ford-prefect/cerbero,BigBrother-International/gst-cerbero,fluendo/cerbero,EricssonResearch/cerbero,brion/cerbero,davibe/cerbero,sdroege/cerbero,GStreamer/cerbero,superdump/cerbero,ylatuya/cerbero,jackjansen/cerbero-2013,flexVDI/cerbero,nicolewu/cerbero,shoreflyer/cerbero,justinjoy/cerbero,sdroege/cerbero,flexVDI/cerbero,shoreflyer/cerbero,ikonst/cerbero,jackjansen/cerbero-2013,atsushieno/cerbero,freedesktop-unofficial-mirror/gstreamer__sdk__cerbero