gdb: re-generate aclocal.m4

I get some changes when running `autoreconf -vf` in the gdb directory,
fix that.

I did a bisect, it appears to have been introduced in this commit, not
sure why we haven't spotted that before.

    commit 862776f2
    Author:     Arsen Arsenovi? <arsen@aarsen.me>
    AuthorDate: Wed Nov 15 12:53:04 2023 +0000
    Commit:     Nick Clifton <nickc@redhat.com>
    CommitDate: Wed Nov 15 12:53:04 2023 +0000

Change-Id: I798d2fbff40c39dbc899832c64e72b2859b536b9