fixing uuid-ossp

I wrote:

I propose to unbreak this contrib module for machines that don't have
uuid.h installed in a directory called ossp (e.g. fc6), by changing
#include <ossp/uuid.h>
to
#include <uuid.h>

People who *do* have it installed in such a directory can add to the
build with a --with-includes configure directive.

If someone feels like fixing this using some configure magic calling
uuid-config in a similar way to the way we use tclConfig.sh, that
might be nice, but I don't have time right now.

I have committed this now.

cheers

andrew