[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.

mono/f-spot,Sanva/f-spot,mans0954/f-spot,dkoeb/f-spot,mans0954/f-spot,mono/f-spot,GNOME/f-spot,Yetangitu/f-spot,GNOME/f-spot,mono/f-spot,Yetangitu/f-spot,GNOME/f-spot,Yetangitu/f-spot,GNOME/f-spot,dkoeb/f-spot,NguyenMatthieu/f-spot,NguyenMatthieu/f-spot,NguyenMatthieu/f-spot,nathansamson/F-Spot-Album-Exporter,mono/f-spot,nathansamson/F-Spot-Album-Exporter,mans0954/f-spot,mans0954/f-spot,Sanva/f-spot,NguyenMatthieu/f-spot,Sanva/f-spot,Yetangitu/f-spot,mans0954/f-spot,mono/f-spot,dkoeb/f-spot,dkoeb/f-spot,nathansamson/F-Spot-Album-Exporter,GNOME/f-spot,nathansamson/F-Spot-Album-Exporter,dkoeb/f-spot,mono/f-spot,Sanva/f-spot,NguyenMatthieu/f-spot,mans0954/f-spot,Yetangitu/f-spot,Sanva/f-spot,dkoeb/f-spot