autogen: USE_GNOME2_MACROS, USE_COMMON_DOC_BUILD

["Thomas H.P. Andersen" <phomes gmail com>]

Hi,

I was wondering why we keep omf.make and xmldocs.make around while
most other modules use  USE_COMMON_DOC_BUILD=yes instead. Is there a
specific reason or was the transition just never done?

Most modules also have "USE_GNOME2_MACROS=1" in their autogen.sh. I
have no idea what it does (google was not my friend) and I can see
that we removed it 2 years ago. Is it just old cruft?

- thomas