Fix two more bugs in fast-path relation locking.

First, the previous code failed to account for the fact that, during Hot
Standby operation, the startup process takes AccessExclusiveLocks on
relations without setting MyDatabaseId.  This resulted in fast path
strong lock counts failing to be incremented with the startup process
took locks, which in turn allowed conflicting lock requests to succeed
when they should not have.  Report by Erik Rijkers, diagnosis by Heikki
Linnakangas.

Second, LockReleaseAll() failed to honor the allLocks and lockmethodid
restrictions with respect to fast-path locks.  It's not clear to me
whether this produces any user-visible breakage at the moment, but it's
certainly wrong.  Rearrange order of operations in LockReleaseAll to fix.
Noted by Tom Lane.
Expand the allowed range of timezone offsets to +/-15:59:59 from Greenwich.

We used to only allow offsets less than +/-13 hours, then it was +/14,
then it was +/-15.  That's still not good enough though, as per today's bug
report from Patric Bechtel.  This time I actually looked through the Olson
timezone database to find the largest offsets used anywhere.  The winners
are Asia/Manila, at -15:56:00 until 1844, and America/Metlakatla, at
+15:13:42 until 1867.  So we'd better allow offsets less than +/-16 hours.

Given the history, we are way overdue to have some greppable #define
symbols controlling this, so make some ... and also remove an obsolete
comment that didn't get fixed the last time.

Back-patch to all supported branches.
Ignore SECURITY DEFINER and SET attributes for a PL's call handler.

It's not very sensible to set such attributes on a handler function;
but if one were to do so, fmgr.c went into infinite recursion because
it would call fmgr_security_definer instead of the handler function proper.
There is no way for fmgr_security_definer to know that it ought to call the
handler and not the original function referenced by the FmgrInfo's fn_oid,
so it tries to do the latter, causing the whole process to start over
again.

Ordinarily such misconfiguration of a procedural language's handler could
be written off as superuser error.  However, because we allow non-superuser
database owners to create procedural languages and the handler for such a
language becomes owned by the database owner, it is possible for a database
owner to crash the backend, which ideally shouldn't be possible without
superuser privileges.  In 9.2 and up we will adjust things so that the
handler functions are always owned by superusers, but in existing branches
this is a minor security fix.

Problem noted by Noah Misch (after several of us had failed to detect
it :-().  This is CVE-2012-2655.
Force PL and range-type support functions to be owned by a superuser.

We allow non-superusers to create procedural languages (with restrictions)
and range datatypes.  Previously, the automatically-created support
functions for these objects ended up owned by the creating user.  This
represents a rather considerable security hazard, because the owning user
might be able to alter a support function's definition in such a way as to
crash the server, inject trojan-horse SQL code, or even execute arbitrary
C code directly.  It appears that right now the only actually exploitable
problem is the infinite-recursion bug fixed in the previous patch for
CVE-2012-2655.  However, it's not hard to imagine that future additions of
more ALTER FUNCTION capability might unintentionally open up new hazards.
To forestall future problems, cause these support functions to be owned by
the bootstrap superuser, not the user creating the parent object.
Update time zone data files to tzdata release 2012c.

DST law changes in Antarctica, Armenia, Chile, Cuba, Falkland Islands,
Gaza, Haiti, Hebron, Morocco, Syria, Tokelau Islands.
Historical corrections for Canada.
Only throw recovery conflicts when InHotStandby. Bug fix to recent
patch to allow Index Only Scans on Hot Standby.

Bug report from Jaime Casanova
Improve comment for GetStableLatestTransactionId().
Update release notes for 9.1.4, 9.0.8, 8.4.12, 8.3.19.
Stamp 9.2beta2.
Provide interim statistics while in mid-checkpoint.
Re-implements similar functionality in 9.1 and previously which
was removed during split of checkpointer and bgwriter.

Requested/spotted by Magnus Hagander
Checkpointer starts before bgwriter to avoid missing fsync requests.
Noted while testing Hot Standby startup.
After any checkpoint, close all smgr files handles in bgwriter
Copy editing of release notes for couple of my items.
Clarify description of covering indexes in release notes
Improve description of pg_stat_statements normalisation in release notes.
Avoid early reuse of btree pages, causing incorrect query results.
When we allowed read-only transactions to skip assigning XIDs
we introduced the possibility that a fully deleted btree page
could be reused. This broke the index link sequence which could
then lead to indexscans silently returning fewer rows than would
have been correct. The actual incidence of silent errors from
this is thought to be very low because of the exact workload
required and locking pre-conditions. Fix is to remove pages only
if index page opaque->btpo.xact precedes RecentGlobalXmin.

Noah Misch, reviewed by Simon Riggs
In pg_upgrade, report pre-PG 8.1 plpython helper functions left in the
public schema that no longer point to valid shared object libraries, and
suggest a solution.