pgsql: initdb: Change authentication defaults

initdb: Change authentication defaults

Change the defaults for the pg_hba.conf generated by initdb to "peer"
for local (if supported, else "md5") and "md5" for host.

(Changing from "md5" to SCRAM is left as a separate exercise.)

"peer" is currently not supported on AIX, HP-UX, and Windows. Users
on those operating systems will now either have to provide a password
to initdb or choose a different authentication method when running
initdb.

Reviewed-by: Julien Rouhaud <rjuju123(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/bec17f0a-ddb1-8b95-5e69-368d9d0a3390%40postgresql.org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/09f08930f0f6fd4a7350ac02f29124b919727198

Modified Files
--------------
doc/src/sgml/ref/initdb.sgml | 17 ++++++++++++++++-
doc/src/sgml/runtime.sgml | 23 +++++++++--------------
doc/src/sgml/standalone-install.xml | 9 ---------
src/bin/initdb/initdb.c | 31 ++++++++++---------------------
src/include/port.h | 5 +++++
src/test/regress/pg_regress.c | 2 +-
6 files changed, 41 insertions(+), 46 deletions(-)