[build] Clean up gnome-doc.m4
[build] Clean up gnome-doc.m4

There's no need to check the version of gnome-doc-utils directly, it's
done by GNOME_DOC_INIT. Also do some code indentation fix-ups.

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