pgsql: Temporary fix for the problem that pg_stat_activity,

Log Message:
-----------
Temporary fix for the problem that pg_stat_activity, inet_client_addr(),
and inet_server_addr() fail if the client connected over a "scoped" IPv6
address.  In this case getnameinfo() will return a string ending with
a poorly-standardized "%something" zone specifier, which these functions
try to feed to network_in(), which won't take it.  So that we don't lose
functionality altogether, suppress the zone specifier before giving the
string to network_in().  Per report from Brian Hirt.

TODO: probably someday the inet type should support scoped IPv6 addresses,
and then this patch should be reverted.

Backpatch to 8.2 ... is it worth going further?

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        network.c (r1.69 -> r1.70)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/network.c.diff?r1=1.69&r2=1.70)
        pgstatfuncs.c (r1.41 -> r1.42)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/pgstatfuncs.c.diff?r1=1.41&r2=1.42)
    pgsql/src/include/utils:
        builtins.h (r1.292 -> r1.293)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h.diff?r1=1.292&r2=1.293)