bug#63337: [PATCH] package-vc--build-documentation: Fix relative @include statements

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 63337@debbugs.gnu.org
> Date: Sun, 07 May 2023 11:40:46 -0700
> From:  Joseph Turner via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> > According to the docs, makeinfo has -I to append the search path, and -P
> > to prepend.  I don't know how well either of the two are supported, but
> > assuming they are, shouldn't -P be preferred?  Or wouldn't it have any
> > effect?
> 
> I am not sure what difference it would make. I don't know if the default
> @include search path includes anything besides the working directory.

It doesn't, according to the Texinfo manual.  Only the current
directory is searched.

> In the attached diff, I have changed -I to -P.

I think it's a mistake: the current directory should searched first.
So -I is better.