pgsql: Add to TODO: > > * Consider not storing a NULL bitmap on disk

Log Message:
-----------
Add to TODO:

* Consider not storing a NULL bitmap on disk if all the NULLs are
trailing

http://archives.postgresql.org/pgsql-hackers/2007-12/msg00624.php
http://archives.postgresql.org/pgsql-patches/2007-12/msg00109.php

Modified Files:
--------------
pgsql/doc:
TODO (r1.2347 -> r1.2348)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/TODO?r1=1.2347&r2=1.2348)
pgsql/doc/src/FAQ:
TODO.html (r1.855 -> r1.856)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html?r1=1.855&r2=1.856)