pgsql: - Add Fortuna PRNG to pgcrypto.

Log Message:
-----------
- Add Fortuna PRNG to pgcrypto.
- Move openssl random provider to openssl.c and builtin provider
  to internal.c
- Make px_random_bytes use Fortuna, instead of giving error.
- Retarget random.c to aquiring system randomness, for initial seeding
  of Fortuna.  There is ATM 2 functions for Windows,
  reader from /dev/urandom and the regular time()/getpid() silliness.

Marko Kreen

Modified Files:
--------------
    pgsql/contrib/pgcrypto:
        Makefile (r1.18 -> r1.19)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgcrypto/Makefile.diff?r1=1.18&r2=1.19)
        internal.c (r1.17 -> r1.18)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgcrypto/internal.c.diff?r1=1.17&r2=1.18)
        openssl.c (r1.20 -> r1.21)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgcrypto/openssl.c.diff?r1=1.20&r2=1.21)
        px.h (r1.12 -> r1.13)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgcrypto/px.h.diff?r1=1.12&r2=1.13)
        random.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgcrypto/random.c.diff?r1=1.10&r2=1.11)