pg_stat_statements forgot to let previous occupant of hook get control too.

pgss_post_parse_analyze() neglected to pass the call on to any earlier
occupant of the post_parse_analyze_hook.  There are no other users of that
hook in contrib/, and most likely none in the wild either, so this is
probably just a latent bug.  But it's a bug nonetheless, so back-patch
to 9.2 where this code was introduced.
Fix typos in comment.
Update obsolete comments.

We no longer have a TLI field in the page header.
Fix incorrect pg_proc.proallargtypes entries for two built-in functions.

pg_sequence_parameters() and pg_identify_object() have had incorrect
proallargtypes entries since 9.1 and 9.3 respectively.  This was mostly
masked by the correct information in proargtypes, but a few operations
such as pg_get_function_arguments() (and thus psql's \df display) would
show the wrong data types for these functions' input parameters.

In HEAD, fix the wrong info, bump catversion, and add an opr_sanity
regression test to catch future mistakes of this sort.

In the back branches, just fix the wrong info so that installations
initdb'd with future minor releases will have the right data.  We
can't force an initdb, and it doesn't seem like a good idea to add
a regression test that will fail on existing installations.

Andres Freund
Reset pg_stat_activity.xact_start during PREPARE TRANSACTION.

Once we've completed a PREPARE, our session is not running a transaction,
so its entry in pg_stat_activity should show xact_start as null, rather
than leaving the value as the start time of the now-prepared transaction.

I think possibly this oversight was triggered by faulty extrapolation
from the adjacent comment that says PrepareTransaction should not call
AtEOXact_PgStat, so tweak the wording of that comment.

Noted by Andres Freund while considering bug #10123 from Maxim Boguk,
although this error doesn't seem to explain that report.

Back-patch to all active branches.
Fix race when updating a tuple concurrently locked by another process

If a tuple is locked, and this lock is later upgraded either to an
update or to a stronger lock, and in the meantime some other process
tries to lock, update or delete the same tuple, it (the tuple) could end
up being updated twice, or having conflicting locks held.

The reason for this is that the second updater checks for a change in
Xmax value, or in the HEAP_XMAX_IS_MULTI infomask bit, after noticing
the first lock; and if there's a change, it restarts and re-evaluates
its ability to update the tuple.  But it neglected to check for changes
in lock strength or in lock-vs-update status when those two properties
stayed the same.  This would lead it to take the wrong decision and
continue with its own update, when in reality it shouldn't do so but
instead restart from the top.

This could lead to either an assertion failure much later (when a
multixact containing multiple updates is detected), or duplicate copies
of tuples.

To fix, make sure to compare the other relevant infomask bits alongside
the Xmax value and HEAP_XMAX_IS_MULTI bit, and restart from the top if
necessary.

Also, in the belt-and-suspenders spirit, add a check to
MultiXactCreateFromMembers that a multixact being created does not have
two or more members that are claimed to be updates.  This should protect
against other bugs that might cause similar bogus situations.

Backpatch to 9.3, where the possibility of multixacts containing updates
was introduced.  (In prior versions it was possible to have the tuple
lock upgraded from shared to exclusive, and an update would not restart
from the top; yet we're protected against a bug there because there's
always a sleep to wait for the locking transaction to complete before
continuing to do anything.  Really, the fact that tuple locks always
conflicted with concurrent updates is what protected against bugs here.)

Per report from Andrew Dunstan and Josh Berkus in thread at
http://www.postgresql.org/message-id/534C8B33.9050807@pgexperts.com

Bug analysis by Andres Freund.
Don't #include utils/palloc.h in common/fe_memutils.h.

This breaks the principle that common/ ought not depend on anything in the
server, not only code-wise but in the headers.  The only arguable advantage
is avoidance of duplication of half a dozen extern declarations, and even
that is rather dubious, considering that the previous coding was wrong
about which declarations to duplicate: it exposed pnstrdup() to frontend
code even though no such function is provided in fe_memutils.c.

On the same principle, don't #include utils/memutils.h in the frontend
build of psprintf.c.  This requires duplicating the definition of
MaxAllocSize, but that seems fine to me: there's no a-priori reason why
frontend code should use the same size limit as the backend anyway.

In passing, clean up some rather odd layout and ordering choices that
were imposed on palloc.h to reduce the number of #ifdefs required by
the previous approach.

Per gripe from Christoph Berg.  There's still more work to do to make
include/common/ clean, but this part seems reasonably noncontroversial.