test_shm_mq: Improve regression tests.

Per discussion with Tom Lane.
libpq:  pass a memory allocation failure error up to PQconndefaults()

Previously user name memory allocation failures were ignored and the
default user name set to NULL.
Again fix initialization of auto-tuned effective_cache_size.

The previous method was overly complex and underly correct; in particular,
by assigning the default value with PGC_S_OVERRIDE, it prevented later
attempts to change the setting in postgresql.conf, as noted by Jeff Janes.
We should just assign the default value with source PGC_S_DYNAMIC_DEFAULT,
which will have the desired priority relative to the boot_val as well as
user-set values.

There is still a gap in this method: if there's an explicit assignment of
effective_cache_size = -1 in the postgresql.conf file, and that assignment
appears before shared_buffers is assigned, the code will substitute 4 times
the bootstrap default for shared_buffers, and that value will then persist
(since it will have source PGC_S_FILE).  I don't see any very nice way
to avoid that though, and it's not a case to be expected in practice.
The existing comments in guc-file.l look forward to a redesign of the
DYNAMIC_DEFAULT mechanism; if that ever happens, we should consider this
case as one of the things we'd like to improve.
Replace the XLogInsert slots with regular LWLocks.

The special feature the XLogInsert slots had over regular LWLocks is the
insertingAt value that was updated atomically with releasing backends
waiting on it. Add new functions to the LWLock API to do that, and replace
the slots with LWLocks. This reduces the amount of duplicated code.
(There's still some duplication, but at least it's all in lwlock.c now.)

Reviewed by Andres Freund.
Properly check for readdir/closedir() failures

Clear errno before calling readdir() and handle old MinGW errno bug
while adding full test coverage for readdir/closedir failures.

Backpatch through 8.4.
Remove MinGW readdir/errno bug workaround fixed on 2003-10-10
Fix build with LWLOCK_STATS or dtrace.

Also fix the name of the dtrace probe for LWLockAcquireOrWait(). The
function was renamed from LWLockWaitUntilFree to LWLockAqcuireOrWait, but
the dtrace probe was neglected.

Pointed out by Andres Freund and the buildfarm.
Fix thinkos in GinLogicValue enum.

It was incorrectly declared as global variable, not an enum type, and
the comments for GIN_FALSE and GIN_TRUE were backwards.
Address ccvalid/ccnoinherit in TupleDesc support functions.

equalTupleDescs() neglected both of these ConstrCheck fields, and
CreateTupleDescCopyConstr() neglected ccnoinherit.  At this time, the
only known behavior defect resulting from these omissions is constraint
exclusion disregarding a CHECK constraint validated by an ALTER TABLE
VALIDATE CONSTRAINT statement issued earlier in the same transaction.
Back-patch to 9.2, where these fields were introduced.
Improve comments about AfterTriggerBeginQuery() query level usage.
Offer triggers on foreign tables.

This covers all the SQL-standard trigger types supported for regular
tables; it does not cover constraint triggers.  The approach for
acquiring the old row mirrors that for view INSTEAD OF triggers.  For
AFTER ROW triggers, we spool the foreign tuples to a tuplestore.

This changes the FDW API contract; when deciding which columns to
populate in the slot returned from data modification callbacks, writable
FDWs will need to check for AFTER ROW triggers in addition to checking
for a RETURNING clause.

In support of the feature addition, refactor the TriggerFlags bits and
the assembly of old tuples in ModifyTable.

Ronan Dunklau, reviewed by KaiGai Kohei; some additional hacking by me.
Don't test xmin/xmax columns of a postgres_fdw foreign table.

Their values are unspecified and system-dependent.

Per buildfarm member kouprey.
Introduce jsonb, a structured format for storing json.

The new format accepts exactly the same data as the json type. However, it is
stored in a format that does not require reparsing the orgiginal text in order
to process it, making it much more suitable for indexing and other operations.
Insignificant whitespace is discarded, and the order of object keys is not
preserved. Neither are duplicate object keys kept - the later value for a given
key is the only one stored.

The new type has all the functions and operators that the json type has,
with the exception of the json generation functions (to_json, json_agg etc.)
and with identical semantics. In addition, there are operator classes for
hash and btree indexing, and two classes for GIN indexing, that have no
equivalent in the json type.

This feature grew out of previous work by Oleg Bartunov and Teodor Sigaev, which
was intended to provide similar facilities to a nested hstore type, but which
in the end proved to have some significant compatibility issues.

Authors: Oleg Bartunov,  Teodor Sigaev, Peter Geoghegan and Andrew Dunstan.
Review: Andres Freund
Fix mis-spelling in jsonb docs.

Per Thom Brown.
Do jsonb regression test input in the conventional way.

This should make the buildfarm happier.
Fix "the the" typos.

Erik Rijkers
Remove dead code and add comments.

'cbuffer' variable was left over from an earlier version of the patch to
rewrite the incomplete split handling.
Fix START_REPLICATION syntax in document.

Enclose "TIMELINE tli" part with brackets because it's optional.

Backport to 9.3 where TIMELINE option was introduced.

Noted by Marko Tiikkaja
Change ginMergeItemPointers to return a palloc'd array.

That seems nicer than making it the caller's responsibility to pass a
suitable-sized array. All the callers were just palloc'ing an array anyway.
Fix ts_rank_cd() to ignore stripped lexemes

Previously, stripped lexemes got a default location and could be
considered if mixed with non-stripped lexemes.

BACKWARD INCOMPATIBILITY CHANGE