pgsql: Add support for RADIUS authentication.

Log Message:
-----------
Add support for RADIUS authentication.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        client-auth.sgml (r1.127 -> r1.128)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/client-auth.sgml?r1=1.127&r2=1.128)
    pgsql/src/backend/libpq:
        auth.c (r1.191 -> r1.192)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/auth.c?r1=1.191&r2=1.192)
        hba.c (r1.195 -> r1.196)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/hba.c?r1=1.195&r2=1.196)
        md5.c (r1.38 -> r1.39)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/md5.c?r1=1.38&r2=1.39)
        pg_hba.conf.sample (r1.71 -> r1.72)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/pg_hba.conf.sample?r1=1.71&r2=1.72)
    pgsql/src/include/libpq:
        hba.h (r1.60 -> r1.61)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/libpq/hba.h?r1=1.60&r2=1.61)
        md5.h (r1.7 -> r1.8)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/libpq/md5.h?r1=1.7&r2=1.8)