possibly undefined macro: dnl (Was: Autoconf 2.50 is released)

[Akim Demaille]

| + After cleaning up the autoupdate warnings, I got the following warning
|   from autoconf:
| 
|         configure.in:1: error: possibly undefined macro: dnl
| 
|   (But I didn't get that warning from dnl lines in my aclocal file!?)
| 
|   I switched to using # as my comment character and things are back to
|   normal.  I don't know how common it is to use dnl in autoconf input
|   files.  If it's common, autoupdate could probably do this for people.

Hi.

Be aware that this message is definitely the sign that something is
going wrong.  If I were you, I'd restore the dnl, and would look for
it in `configure' itself.  It means that somewhere you were relying on
the broken quotation of 2.13, or maybe that it is 2.50, trying to fix
these issues, that broke you source.

Looking for dnl in the output should give you an hint on where in the
source things went wrong.

Please, keep us informed.