AC_LIBOBJ and libsources

[Akim Demaille]

I need help from both communities.

It is clear that Autoconf macros needs a means to tell Automake that
some file is to be shipped.  The most typical use is LIBOBJ.  But
there is often more than the .c file to ship, e.g., getopt.h.

So the problem is what does Automake need, and what are the macros
Autoconf should provide.

1. Does Automake need to know what are the files that can actually be
   in LIBOBJ, or headers can be included?

2. Do we really care about extra dependencies?  In the case of rx.h
   and regex.h, I can't see any actual problem is we depend upon rx.h
   but use regex.h.  And anyway, is this still relevant today?