pgsql: Add: > * Allow accurate statistics to be collected on indexes

Log Message:
-----------
Add:

* Allow accurate statistics to be collected on indexes with more than
one column

Modified Files:
--------------
pgsql/doc:
TODO (r1.1379 -> r1.1380)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.1379&r2=1.1380)