.pgpass's behavior has changed

Hello.

I noticed that the precedence between host and hostaddr in a
connection string is reversed in regard to .pgpass lookup in
devel.

For example the following connection string uses a .pgpass entry
with "127.0.0.1", not "hoge".

"host=hoge hostaddr=127.0.0.1 port=5432 dbname=postgres"

This change was introdueced by the commit
274bb2b3857cc987cfa21d14775cae9b0dababa5 and the current behavior
contradicts the documentation.

https://www.postgresql.org/docs/devel/static/libpq-connect.html

> hostaddr
> ...
> Note that authentication is likely to fail if host is not the
> name of the server at network address hostaddr. Also, note that
> host rather than hostaddr is used to identify the connection in
> a password file (see Section 33.15, “The Password File”).

I think this should be fixed for the same reason with the
following commit.

> commit 11003eb55658df0caf183eef69c7a97d56a4f2d7
> Author: Robert Haas <rhaas(at)postgresql(dot)org>
> Date: Thu Dec 1 14:36:39 2016 -0500
>
> libpq: Fix inadvertent change in PQhost() behavior.

But the above also leaves a bug so I sent another patch to fix
it. The attched patch restores the 9.6's beavior of looking up
.pgpass file in the same manner to the aother patch.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center