pgsql: Rework PostgresNode's psql method

Rework PostgresNode's psql method

This makes the psql() method much more capable: it captures both stdout
and stderr; it now returns the psql exit code rather than stdout; a
timeout can now be specified, as can ON_ERROR_STOP behavior; it gained a
new "on_error_die" (defaulting to off) parameter to raise an exception
if there's any problem.  Finally, additional parameters to psql can be
passed if there's need for further tweaking.

For convenience, a new safe_psql() method retains much of the old
behavior of psql(), except that it uses on_error_die on, so that
problems like syntax errors in SQL commands can be detected more easily.

Many existing TAP test files now use safe_psql, which is what is really
wanted.  A couple of ->psql() calls are now added in the commit_ts
tests, which verify that the right thing is happening on certain errors.
Some ->command_fails() calls in recovery tests that were verifying that
psql failed also became ->psql() calls now.

Author: Craig Ringer. Some tweaks by Álvaro Herrera
Reviewed-By: Michaël Paquier

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/2c83f435a3deca745c666e9778229d64cb2dfc79

Modified Files
--------------
src/bin/pg_basebackup/t/010_pg_basebackup.pl  |  22 +--
src/bin/pgbench/t/001_pgbench.pl              |   2 +-
src/bin/scripts/t/010_clusterdb.pl            |   2 +-
src/bin/scripts/t/030_createlang.pl           |   2 +-
src/bin/scripts/t/050_dropdb.pl               |   2 +-
src/bin/scripts/t/070_dropuser.pl             |   2 +-
src/bin/scripts/t/090_reindexdb.pl            |   2 +-
src/test/modules/commit_ts/t/001_base.pl      |   8 +-
src/test/modules/commit_ts/t/002_standby.pl   |  22 ++-
src/test/modules/commit_ts/t/003_standby_2.pl |  20 +-
src/test/perl/PostgresNode.pm                 | 268 ++++++++++++++++++++++++--
src/test/recovery/t/001_stream_rep.pl         |  20 +-
src/test/recovery/t/002_archiving.pl          |  10 +-
src/test/recovery/t/003_recovery_targets.pl   |  26 +--
src/test/recovery/t/004_timeline_switch.pl    |  10 +-
src/test/recovery/t/005_replay_delay.pl       |  10 +-
16 files changed, 326 insertions(+), 102 deletions(-)