Re: more efficient AS_EXIT

[Paolo Bonzini]

> The _only_ place where AS_EXIT changed semantics from what
> it had in 2.63 to what it has now in autoconf.git is if you:
> 1) use it without arguments, and
> 2) $? is greater than 1

Yes, and I understand that the result *is* better in general if the
default argument is not 1.  And I appreciate your effort, but the
semantics when $? = 0 are just too unobvious.  I think we *can*
sacrifice backwards-compatibility and default to $?, because there is a
reason why the macro was almost unused in the wild; the reason being
that there are pretty good documented AC_* macros to exit with an error
message, so no one should need to use AS_EXIT except in pure M4sh
scripts.  In fact, the only user within configure scripts was in
kpathsea, while Libtool is using it in the generated config.lt file.

Paolo