pgsql: Generate the various .def files for libpq DLLs from a single list

Log Message:
-----------
Generate the various .def files for libpq DLLs from a single list of
exportable functions.  The .def files are removed from CVS, but will
still be present in distribution tarballs, since we can't assume that
Windows boxes will have sed.

Modified Files:
--------------
    pgsql/src/interfaces/libpq:
        Makefile (r1.118 -> r1.119)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/Makefile.diff?r1=1.118&r2=1.119)

Added Files:
-----------
    pgsql/src/interfaces/libpq:
        .cvsignore (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/.cvsignore?rev=1.1&content-type=text/x-cvsweb-markup)
        exports.txt (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/exports.txt?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/src/interfaces/libpq:
        blibpqdll.def
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/blibpqdll.def)
        libpqddll.def
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpqddll.def)
        libpqdll.def
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpqdll.def)