keywords in initdb are case-sensitive?

In miracee's review of Peter's patch for new -A options in initdb (in
commitfest app only), it is noted that pg_hba.conf keyword parsing is
done in a case sensitive manner.  So if you write "Trust" rather than
"trust", it's not recognized.

This seemed pretty nonsensical to me, and it's not documented, so I came
up with the trivial attached patch.

Comparisons to user and database names and the like are unchanged and
thus require matching case.

Thoughts?

-- 
Álvaro Herrera <alvherre@alvh.no-ip.org>