unconditional inclusion of argz.h; missing declared functions in argz.h

[Juan Manuel Guerrero]

I have tried to compile CVS head checked out today using DJGPP.
It failed because /install-info/install-info.c unconditionally includes
the header argz.h that is currently not available with DJGPP.
Inspecting the configure script showed me that it is never tested
for existance nor usability of the header.  Inspecting the files provided
in /gnulib has also showed me that none of the files declared by argz.h
are distributed with texinfo.  Although all this is a DJGPP problem, may be
it may also be of importance for other systems.
Because I am not familiar enough with gnulib and the bootstrap procedure
of texinfo I prefer not to provide a solution for this issue.  May be someone
else is so kind to solve this for me.

TIA,
Juan M. Guerrero