pgsql: Export only required symbols in libpq on Win32.

Log Message:
-----------
Export only required symbols in libpq on Win32.

Magnus Hagander

Modified Files:
--------------
    pgsql/src:
        Makefile.shlib (r1.85 -> r1.86)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.shlib.diff?r1=1.85&r2=1.86)
    pgsql/src/interfaces/libpq:
        Makefile (r1.117 -> r1.118)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/Makefile.diff?r1=1.117&r2=1.118)
        blibpqdll.def (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/blibpqdll.def.diff?r1=1.10&r2=1.11)
        fe-secure.c (r1.54 -> r1.55)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-secure.c.diff?r1=1.54&r2=1.55)
        libpq-fe.h (r1.109 -> r1.110)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpq-fe.h.diff?r1=1.109&r2=1.110)
        libpqddll.def (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpqddll.def.diff?r1=1.2&r2=1.3)
        libpqdll.def (r1.26 -> r1.27)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/libpqdll.def.diff?r1=1.26&r2=1.27)