[PATCH] [4/14] Completes renaming of configure.in files to .ac

[Michael Darling]

> Since all configure files are generated from them, this patch must be
> checked in first.
> But some of them are imported and some imported packages still use configure.in,
> not configure.ac.
>
> What is the real value of changing "configure.in" in comments/messages to
> "configure.ac" when both are used in packages?

Before binutils commit 35eafcc7 a year ago, I'm pretty sure everything
in binutils-gdb used the .in extension.  And, around that time, I'm
pretty sure everything in gcc also used the .in extension.
Binutils-gdb partially moved over to the .ac extension, and gcc
completely moved over to the .ac extension.

This left a lot of references pointing to the wrong extension.
Allowing both extensions, even if made to work now, will break again
someday.  I think having comments, messages, and documentation point
semi-randomly to one or the other is inviting future confusion.

I think the only way to permanently fix this is to complete the
(almost complete) transition to the .ac extension.  I would have
probably personally left everything as a .in extension, since for now
there's no real difference, but I think the transition should either
be complete or not there at all.  Since the conversion already
started, I think all references anywhere to the .in extension should
be updated.  (Unless in a historical context like a ChangeLog.)

Which imported packages use configure.in?  I'm happy to submit patches
for those, too.