Remove broken PGXS code for pg_xlogdump

With the PGXS boilerplate in place, pg_xlogdump currently fails with an
ominous error message that certain targets cannot be built because
certain files do not exist.  Remove that and instead throw a quick error
message alerting the user of the actual problem, which should be easier
to diagnose that the statu quo.

Andres Freund
Add WaitForLockers in lmgr, refactoring index.c code

This is in support of a future REINDEX CONCURRENTLY feature.

Michael Paquier
Adjust C comments that would be wrap-able.
Fix copy/paste error
doc: fix hstore_to_json_loose() doc wording
psql: Set up cancel handler later

The cancel handler was uselessly set up even before the first connection
was opened.  By setting it up afterwards, the user can use Ctrl+C to
abort psql if the initial connection attempt hangs.

Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Ryan Kelly <rpkelly22@gmail.com>
doc: Correct psycopg URL
Minor GIN code refactoring.

It makes for cleaner code to have separate Get/Add functions for PostingItems
and ItemPointers.  A few callsites that have to deal with both types need to
be duplicated because of this, but all the callers have to know which one
they're dealing with anyway. Overall, this reduces the amount of casting
required.

Extracted from Alexander Korotkov's larger patch to change the data page
format.
psql: Make \pset without arguments show all settings.

Gilles Darold, reviewed by Pavel Stehule
Add DISCARD SEQUENCES command.

DISCARD ALL will now discard cached sequence information, as well.

Fabrízio de Royes Mello, reviewed by Zoltán Böszörményi, with some
further tweaks by me.
Fix silly thinko in ResetSequenceCaches.

Report from Kevin Hale Boyes.
doc: Add missing words to bgworker docs.

Maciek Sakrejda
Issue error on SET outside transaction block in some cases

Issue error for SET LOCAL/CONSTRAINTS/TRANSACTION outside a transaction
block, as they have no effect.

Per suggestion from Morten Hustveit
isolationtester: Allow tuples to be returned in more places

Previously, isolationtester would forbid returning tuples in
session-specific teardown (but not global teardown), as well as in
global setup.  Allow these places to return tuples, too.
Make some isolationtester specs more complete

Also, make sure they pass on all transaction isolation levels.
add multixact-no-deadlock to schedule
Merge branch 'master' into matview