uuid.h on Debian

Compiling contrib/uuid-ossp on my Debian laptop failed, because
apparently on Debian the uuid.h header is installed as ossp/uuid.h.
That's probably to avoid confusion with other UUID implementations;
there's at least one included with e2fsprogs, but fortunately the header
file for that is called uuid/uuid.h.

Attached is a patch that adds some autoconf magic to deal with that. I'm
testing ossp/uuid.h first, because presumably if that exists it's the
right one, while I suspect there might be other files called just uuid.h
on other systems that are not the same thing.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com