[build] Allow building without gnome-doc-utils
[build] Allow building without gnome-doc-utils

stsundermann/banshee,arfbtwn/banshee,petejohanson/banshee,petejohanson/banshee,allquixotic/banshee-gst-sharp-work,ixfalia/banshee,GNOME/banshee,stsundermann/banshee,Dynalon/banshee-osx,lamalex/Banshee,Dynalon/banshee-osx,Dynalon/banshee-osx,dufoli/banshee,mono-soc-2011/banshee,stsundermann/banshee,arfbtwn/banshee,petejohanson/banshee,Carbenium/banshee,Carbenium/banshee,Carbenium/banshee,GNOME/banshee,Dynalon/banshee-osx,mono-soc-2011/banshee,GNOME/banshee,Dynalon/banshee-osx,petejohanson/banshee,dufoli/banshee,GNOME/banshee,ixfalia/banshee,Carbenium/banshee,ixfalia/banshee,ixfalia/banshee,arfbtwn/banshee,mono-soc-2011/banshee,stsundermann/banshee,mono-soc-2011/banshee,directhex/banshee-hacks,directhex/banshee-hacks,babycaseny/banshee,mono-soc-2011/banshee,dufoli/banshee,arfbtwn/banshee,Carbenium/banshee,directhex/banshee-hacks,dufoli/banshee,stsundermann/banshee,allquixotic/banshee-gst-sharp-work,directhex/banshee-hacks,petejohanson/banshee,directhex/banshee-hacks,Dynalon/banshee-osx,mono-soc-2011/banshee,GNOME/banshee,lamalex/Banshee,ixfalia/banshee,Carbenium/banshee,stsundermann/banshee,arfbtwn/banshee,babycaseny/banshee,arfbtwn/banshee,ixfalia/banshee,allquixotic/banshee-gst-sharp-work,lamalex/Banshee,lamalex/Banshee,GNOME/banshee,GNOME/banshee,lamalex/Banshee,dufoli/banshee,arfbtwn/banshee,directhex/banshee-hacks,dufoli/banshee,stsundermann/banshee,mono-soc-2011/banshee,babycaseny/banshee,stsundermann/banshee,arfbtwn/banshee,babycaseny/banshee,allquixotic/banshee-gst-sharp-work,babycaseny/banshee,allquixotic/banshee-gst-sharp-work,Dynalon/banshee-osx,babycaseny/banshee,dufoli/banshee,ixfalia/banshee,allquixotic/banshee-gst-sharp-work,petejohanson/banshee,ixfalia/banshee,Dynalon/banshee-osx,GNOME/banshee,babycaseny/banshee,dufoli/banshee,lamalex/Banshee,babycaseny/banshee