[PATCH V4] configure.ac: Fallback to older detection code if pkg-config can't find expat

[Bryce Harrington]

On Fri, Feb 06, 2015 at 12:15:20PM +0000, Andrew Oakley wrote:
> On 03/02/15 22:26, Bill Spitzak wrote:
> > This paritally reverts commit a4afd90f9f0c27ed5f3f313b915c260673f8be34.
> > 
> > On older expat versions (ie the one on Ubuntu 12.04) there is no pkg-config
> > file, so fall back to a test for the header and library. In addition the
> > source for expat does not seem to be in a git repository but in cvs instead
> > and it seems preferrable to not require cvs to build wayland.
> > 
> > The restored test has been updated to use AC_SEARCH_LIBS. This version
> > uses empty square brackets for the unused branches, similar to many other
> > if statements in configure.ac.
> 
> This seems fine to me and it seems to generate the right stuff in the
> configure script.  It certainly seems better than what was there before,
> but I'm not an autoconf guru.
> 
> Apologies for poking the bear, thanks for trying to fix it properly!
> 
> What I was trying to do was compile expat and wayland-scanner for host
> with a non-standard prefix, then cross-compile wayland itself using the
> tools we just built.  We could have passed extra configure options, but
> the pkg-config solution "just works" for the majority of packages.  I
> didn't think changing this would cause any trouble as expat has been
> distributing pc files for many years.
> 
> Reviewed-by: Andrew Oakley <aoakley at espial.com>

On recommendation from pq, fixing this in autoconf.  This won't hurt
anything and potentially removes a regression for users with ancient
expat's.

Thanks, applied.

   76fe89e..371a9e0  master -> master

Bryce