bug#65323: build failure on Alpine Linux

[Eli Zaretskii <eliz@gnu.org>]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Bruno Haible <bruno@clisp.org>,  65323@debbugs.gnu.org
> Date: Thu, 17 Aug 2023 11:13:58 +0200
> 
> >>>>> On Thu, 17 Aug 2023 08:44:36 +0300, Eli Zaretskii <eliz@gnu.org> said:
> 
>     >> From: Bruno Haible <bruno@clisp.org>
>     >> Cc: 65323@debbugs.gnu.org
>     >> Date: Thu, 17 Aug 2023 00:59:52 +0200
>     >> 
>     >> Eli Zaretskii wrote:
>     >> 
>     >> > Are we using some feature that is not standard in Awk?
>     >> 
> 
> I think busyboxʼs awk is being more strict about regexp interval
> expressions than eg gawk.
> 
>     Eli> Not sure if the above is at all relevant, since the error message you
>     Eli> quoted comes from the build-aux/make-info-dir script, so maybe you
>     Eli> should ignore everything I wrote above, and look just at that script
>     Eli> and the Awk commands it runs.  (It's a poor-man's install-info.)
> 
> The following works for both gawk 5.2.1 and busybox awk 1.37.

Thanks, please install this on master.