aclocal.m4

Ok, I've split todays commit into three, the first two already done had some
bits in JDBC & the first set of tools into contrib.

This is the third, and deals with enabling JDBC to be compiled with the main
source.

What it does is add a new option to configure: --with-java

This option tells configure to look for ant (our build tool of choice) and
if found, it then compiles both the JDBC driver and the new tools as part
of the normal make.

Also, when the postgresql install is done, all the .jar files are also
installed into the ${PGLIB}/java directory (thought best to keep then separate)

Now I had some conflicts when this applied so could someone please double check
that everything is ok?

Peter