Is AC_DEFUN_ONCE supposed to be public?

[Alexandre Duret-Lutz]

Kelley sent in a patch to have aclocal recognize AC_DEFUN_ONCE
definitions.

The AC_DEFUN_ONCE macro was introduced in Autoconf 2.50 and is
not mentioned in the manual.  I didn't know about it, until that
patch came in.  Anyway since it's undocumented it means it's an
internal macro that people shouldn't depend on, and aclocal
should not care about it.

On the other hand, since some people are using it, I presume
there is a need for it.  Is using AC_DEFUN_ONCE bad style or
not?  In the latter case maybe we should document it (in
addition to having it supported by aclocal).
-- 
Alexandre Duret-Lutz