pgsql: Add: * Test to see if calling PreallocXlogFiles() from the

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

* Test to see if calling PreallocXlogFiles() from the background writer
will help with WAL segment creation latency

http://archives.postgresql.org/pgsql-patches/2007-06/msg00340.php

Modified Files:
--------------
pgsql/doc:
TODO (r1.2305 -> r1.2306)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/TODO?r1=1.2305&r2=1.2306)
pgsql/doc/src/FAQ:
TODO.html (r1.814 -> r1.815)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html?r1=1.814&r2=1.815)