address root cause of compilation failures:

address root cause of compilation failures:

The affected code wasn't even being compiled on my system,
because HAVE_NL_LANGINFO was not defined.  On other systems, where
vasnprintf.m4 determines it needs %A or %a replacement support, it
_would_ check for nl_langinfo, and expose the compilation failure.
* m4/jm-macros.m4: Check for nl_langinfo, required by sort.c.