bug#57420: 29.0.50; Failure configuring Emacs with animated WebP support

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 25 Aug 2022 23:59:40 +0200
> From:  Daniel Martín via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> If WebP animated support requires -lwebpdemux, I think we could require
> the libwebpdemux module instead (part of the libwebp package), whose
> linker flags include "-lwebp -lwebpdemux".  The following patch fixes
> the compilation for me:
> 
> diff --git a/configure.ac b/configure.ac
> index 6ca3052ea3..4590ed3506 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -2773,12 +2773,9 @@ AC_DEFUN
>     || test "${HAVE_W32}" = "yes" || test "${HAVE_NS}" = "yes" \
>     || test "${HAVE_BE_APP}" = "yes" || test "${HAVE_PGTK}" = "yes"; then
>        WEBP_REQUIRED=0.6.0
> -      WEBP_MODULE="libwebp >= $WEBP_REQUIRED"
> +      WEBP_MODULE="libwebpdemux >= $WEBP_REQUIRED"
>  
>        EMACS_CHECK_MODULES([WEBP], [$WEBP_MODULE])
> -      if test "$HAVE_WEBP" = "yes"; then
> -        WEBP_LIBS="-lwebp -lwebpdemux"
> -      fi
>        AC_SUBST([WEBP_CFLAGS])
>        AC_SUBST([WEBP_LIBS])
>     fi
> 
> I checked that the built Emacs has WebP support.
> 
> What do you think?

LGTM, thanks.