Hi Zack,

Here are patches to sync autoconf with gnulib:
 
   AC_FUNC_CHOWN                   chown.m4 -> functions.m4
 
   AC_FUNC_GETGROUPS               getgroups.m4 -> functions.m4
 
   AC_FUNC_MBRTOWC                 mbrtowc.m4 -> functions.m4
 
   AC_TYPE_MBSTATE_T               mbstate_t.m4 -> types.m4
 
   AC_FUNC_GETMNTENT               mountlist.m4 -> functions.m4
 
   AC_FUNC_OBSTACK                 obstack.m4 -> functions.m4

The changes are mostly minor; the main purpose is
  1) to be able to do this sync more easily in the future,
  2) to wrap some of these definitions in
       m4_version_prereq([2.70.1], [], [
     in Gnulib.

There are still some remaining differences: Gnulib offers a
configure option --enable-cross-guesses={conservative|risky}
that determines how cross-compilation guesses work in case of
unknown platforms. --enable-cross-guesses=conservative is
the default. However, when an operating system developer (on a
platform which is not yet known to gnulib) builds packages for
their platform, they want to expose, not hide, possible platform
bugs; in this case, --enable-cross-guesses=risky is the appropriate
choice. Autoconf does not have such an option.

Bruno