Re: expose m4_PACKAGE_VERSION,m4_version_compare

[Paolo Bonzini]

> +** New m4sugar macro m4_AUTOCONF_VERSION.  Also, document the m4sugar macros
> +   m4_ifndef, m4_version_compare, and m4_PACKAGE_VERSION (available
> +   without documentation since at least autoconf 2.53), in part so
> +   that packages can make decisions based on the current version of
> +   autoconf used to evaluate a given configure.ac.  The name
> +   m4_PACKAGE_VERSION may be marked obsolescent in a future release.

Sorry to come in late, but why not AC_VERSION and defining it in 
general.m4?  Long term, m4sugar might be detached completely from 
Autoconf (e.g. it could be distributed with M4 2.x) and already now it 
is used by Bison.

Paolo