with OPAQUE, as per recent pghackers discussion. I still want to do some
more work on the 'cstring' pseudo-type, but I'm going to commit the bulk
of the changes now before the tree starts shifting under me ...
under libdir, for a cleaner separation in the installation layout
and compatibility with binary packaging standards. Point backend's
default search location there. The contrib modules are also
installed in the said location, giving them the benefit of the
default search path as well. No changes in user interface
nevertheless.