Reactivate distribution of generated documentation
Reactivate distribution of generated documentation

* build/doc-reference.am (dist_*_DATA): Add dist_ prefix.
(*CLEANFILES): Clean files on distclean or maintainer-clean.
(maintainer-clean-local): Rename from clean-local.
(doc_dependencies): Assign documentation dependencies indirectly
depending on the maintainer mode setting.

GNOME/librsvgmm,GNOME/librsvgmm,GNOME/librsvgmm