Fix VPATH builds, broken by my recent commit to speed up tuplesorting.

The relevant commit is 337b6f5ecf05b21b5e997986884d097d60e4e3d0.
Run a portal's cleanup hook immediately when pushing it to FAILED state.

This extends the changes of commit 6252c4f9e201f619e5eebda12fa867acd4e4200e
so that we run the cleanup hook earlier for failure cases as well as
success cases.  As before, the point is to avoid an assertion failure from
an Assert I added in commit a874fe7b4c890d1fe3455215a83ca777867beadd, which
was meant to check that no user-written code can be called during portal
cleanup.  This fixes a case reported by Pavan Deolasee in which the Assert
could be triggered during backend exit (see the new regression test case),
and also prevents the possibility that the cleanup hook is run after
portions of the portal's state have already been recycled.  That doesn't
really matter in current usage, but it foreseeably could matter in the
future.

Back-patch to 9.1 where the Assert in question was added.
Invent on_exit_nicely for pg_dump.

Per recent discussions on pgsql-hackers regarding parallel pg_dump.
Refactor pg_dump.c to avoid duplicating returns-one-row check.

Any patches apt to get broken have probably already been broken by the
error-handling cleanups I just did, so we might as well clean this up
at the same time.
pg_dump: Remove global connection pointer.

Parallel pg_dump wants to have multiple ArchiveHandle objects, and
therefore multiple PGconns, in play at the same time.  This should
be just about the end of the refactoring that we need in order to
make that workable.
pg_dump: Miscellaneous tightening based on recent refactorings.

Use exit_horribly() and ExecuteSqlQueryForSingleRow() in various
places where it's equivalent, or nearly equivalent, to the prior
coding. Apart from being more compact, this also makes the error
messages for the wrong-number-of-tuples case more consistent.
Improve statistics estimation to make some use of DISTINCT in sub-queries.

Formerly, we just punted when trying to estimate stats for variables coming
out of sub-queries using DISTINCT, on the grounds that whatever stats we
might have for underlying table columns would be inapplicable.  But if the
sub-query has only one DISTINCT column, we can consider its output variable
as being unique, which is useful information all by itself.  The scope of
this improvement is pretty narrow, but it costs nearly nothing, so we might
as well do it.  Per discussion with Andres Freund.

This patch differs from the draft I submitted yesterday in updating various
comments about vardata.isunique (to reflect its extended meaning) and in
tweaking the interaction with security_barrier views.  There does not seem
to be a reason why we can't use this sort of knowledge even when the
sub-query is such a view.
Fix longstanding error in contrib/intarray's int[] & int[] operator.

The array intersection code would give wrong results if the first entry of
the correct output array would be "1".  (I think only this value could be
at risk, since the previous word would always be a lower-bound entry with
that fixed value.)

Problem spotted by Julien Rouhaud, initial patch by Guillaume Lelarge,
cosmetic improvements by me.
Sync regex code with Tcl 8.5.11.

Sync our regex code with upstream changes since last time we did this,
which was Tcl 8.5.0 (see commit df1e965e12cdd48c11057ee6e15346ee2b8b02f5).

There are no functional changes here; the main point is just to lay down
a commit-log marker that somebody has looked at this recently, and to do
what we can to keep the two codebases comparable.
Make sure all connection paramters are used in call to PQconnectdbParams.
Windows doesn't have strtok_r, so let's use strtok_s instead.
gcc on Windows does not know about strtok_s.
Update expected/collate.linux.utf8.out for recent plpgsql changes.

This file was missed in commit 4c6cedd1b014abf2046886a9a92e10e18f0d658e.
In ecpglib rewrote code that used strtok_r to not use library functions
anymore. This way we don't have to worry which compiler on which OS offers
which version of strtok.
Improve pretty printing of viewdefs.

Some line feeds are added to target lists and from lists to make
them more readable. By default they wrap at 80 columns if possible,
but the wrap column is also selectable - if 0 it wraps after every
item.

Andrew Dunstan, reviewed by Hitoshi Harada.
Create the beginnings of internals documentation for the regex code.

Create src/backend/regex/README to hold an implementation overview of
the regex package, and fill it in with some preliminary notes about
the code's DFA/NFA processing and colormap management.  Much more to
do there of course.

Also, improve some code comments around the colormap and cvec code.
No functional changes except to add one missing assert.
Add caching of ctype.h/wctype.h results in regc_locale.c.

While this doesn't save a huge amount of runtime, it still seems worth
doing, especially since I realized that the data copying I did in my first
draft was quite unnecessary.  In this version, once we have the results
cached, getting them back for re-use is really very cheap.

Also, remove the hard-wired limitation to not consider wctype.h results for
character codes above 255.  It turns out that we can't push the limit as
far up as I'd originally hoped, because the regex colormap code is not
efficient enough to cope very well with character classes containing many
thousand letters, which a Unicode locale is entirely capable of producing.
Still, we can push it up to U+7FF (which I chose as the limit of 2-byte
UTF8 characters), which will at least make Eastern Europeans happy pending
a better solution.  Thus, this commit resolves the specific complaint in
bug #6457, but not the more general issue that letters of non-western
alphabets are mostly not recognized as matching [[:alpha:]].
Fix regex back-references that are directly quantified with *.

The syntax "\n*", that is a backref with a * quantifier directly applied
to it, has never worked correctly in Spencer's library.  This has been an
open bug in the Tcl bug tracker since 2005:
https://sourceforge.net/tracker/index.php?func=detail&aid=1115587&group_id=10894&atid=110894

The core of the problem is in parseqatom(), which first changes "\n*" to
"\n+|" and then applies repeat() to the NFA representing the backref atom.
repeat() thinks that any arc leading into its "rp" argument is part of the
sub-NFA to be repeated.  Unfortunately, since parseqatom() already created
the arc that was intended to represent the empty bypass around "\n+", this
arc gets moved too, so that it now leads into the state loop created by
repeat().  Thus, what was supposed to be an "empty" bypass gets turned into
something that represents zero or more repetitions of the NFA representing
the backref atom.  In the original example, in place of
	^([bc])\1*$
we now have something that acts like
	^([bc])(\1+|[bc]*)$
At runtime, the branch involving the actual backref fails, as it's supposed
to, but then the other branch succeeds anyway.

We could no doubt fix this by some rearrangement of the operations in
parseqatom(), but that code is plenty ugly already, and what's more the
whole business of converting "x*" to "x+|" probably needs to go away to fix
another problem I'll mention in a moment.  Instead, this patch suppresses
the *-conversion when the target is a simple backref atom, leaving the case
of m == 0 to be handled at runtime.  This makes the patch in regcomp.c a
one-liner, at the cost of having to tweak cbrdissect() a little.  In the
event I went a bit further than that and rewrote cbrdissect() to check all
the string-length-related conditions before it starts comparing characters.
It seems a bit stupid to possibly iterate through many copies of an
n-character backreference, only to fail at the end because the target
string's length isn't a multiple of n --- we could have found that out
before starting.  The existing coding could only be a win if integer
division is hugely expensive compared to character comparison, but I don't
know of any modern machine where that might be true.

This does not fix all the problems with quantified back-references.  In
particular, the code is still broken for back-references that appear within
a larger expression that is quantified (so that direct insertion of the
quantification limits into the BACKREF node doesn't apply).  I think fixing
that will take some major surgery on the NFA code, specifically introducing
an explicit iteration node type instead of trying to transform iteration
into concatenation of modified regexps.

Back-patch to all supported branches.  In HEAD, also add a regression test
case for this.  (It may seem a bit silly to create a regression test file
for just one test case; but I'm expecting that we will soon import a whole
bunch of regex regression tests from Tcl, so might as well create the
infrastructure now.)
Fix a couple of cases of JSON output.

First, as noted by Itagaki Takahiro, a datum of type JSON doesn't
need to be escaped. Second, ensure that numeric output not in
the form of a legal JSON number is quoted and escaped.
Don't reject threaded Python on FreeBSD.

According to Chris Rees, this has worked for awhile, and the current
FreeBSD port is removing the test anyway.