pgsql: Sync dlopen error handling for the *BSDs ...

Log Message:
-----------
Sync dlopen error handling for the *BSDs ... seems to me I've done this
before, but they were out of sync again.  Per Kris Jurka.

Modified Files:
--------------
    pgsql/src/backend/port/dynloader:
        freebsd.c (r1.22 -> r1.23)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/dynloader/freebsd.c.diff?r1=1.22&r2=1.23)
        netbsd.c (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/dynloader/netbsd.c.diff?r1=1.16&r2=1.17)
        openbsd.c (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/dynloader/openbsd.c.diff?r1=1.16&r2=1.17)