pgsql: Remove bogus commutator marking --- the module doesn't actually

Log Message:
-----------
Remove bogus commutator marking --- the module doesn't actually supply
any commutator operator for =(chkpass,text), so this was creating a
shell operator that would fail on use. Found by opr_sanity testing.

Modified Files:
--------------
pgsql/contrib/chkpass:
chkpass.sql.in (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/chkpass/chkpass.sql.in?r1=1.6&r2=1.7)
uninstall_chkpass.sql (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/chkpass/uninstall_chkpass.sql?r1=1.2&r2=1.3)