The attached patch enables the contrib subtree to build cleanly under

Cygwin with the possible exception of mSQL-interface.  Since I don't
have mSQL installed, I skipped this tool.

Except for dealing with a missing getopt.h (oid2name) and HUGE (seg),
the bulk of the patch uses the standard PostgreSQL approach to deal with
Windows DLL issues.

I tested the build aspect of this patch under Cygwin and Linux without
any ill affects.  Note that I did not actually attempt to test the code
for functionality.

The procedure to apply the patch is as follows:

    $ # save the attachment as /tmp/contrib.patch
    $ # change directory to the top of the PostgreSQL source tree
    $ patch -p0 </tmp/contrib.patch

Jason