In WAL replay, restore GIN metapage unconditionally to avoid torn page.

We don't take a full-page image of the GIN metapage; instead, the WAL record
contains all the information required to reconstruct it from scratch. But
to avoid torn page hazards, we must re-initialize it from the WAL record
every time, even if it already has a greater LSN, similar to how normal full
page images are restored.

This was highly unlikely to cause any problems in practice, because the GIN
metapage is small. We rely on an update smaller than a 512 byte disk sector
to be atomic elsewhere, at least in pg_control. But better safe than sorry,
and this would be easy to overlook if more fields are added to the metapage
so that it's no longer small.

Reported by Noah Misch. Backpatch to all supported versions.
Prevent interrupts while reporting non-ERROR elog messages.

This should eliminate the risk of recursive entry to syslog(3), which
appears to be the cause of the hang reported in bug #9551 from James
Morton.

Arguably, the real problem here is auth.c's willingness to turn on
ImmediateInterruptOK while executing fairly wide swaths of backend code.
We may well need to work at narrowing the code ranges in which the
authentication_timeout interrupt is enabled.  For the moment, though,
this is a cheap and reasonably noninvasive fix for a field-reported
failure; the other approach would be complex and not necessarily
bug-free itself.

Back-patch to all supported branches.
Add missing #include.

Commit 31400a673 and siblings added a check_stack_depth() call in
contrib/intarray/_int_bool.c, but neglected to note that in our oldest
branches that file didn't have the #include that defines that function.
This results in a fortunately-harmless compiler warning.  Per buildfarm.
Update time zone data files to tzdata release 2014a.

DST law changes in Fiji, Turkey; historical changes in Israel, Ukraine.
Fix advertised dispsize for libpq's sslmode connection parameter.

"8" was correct back when "disable" was the longest allowed value, but
since "verify-full" was added, it should be "12".  Given the lack of
complaints, I wouldn't be surprised if nobody is actually using these
values ... but still, if they're in the API, they should be right.

Noticed while pursuing a different problem.  It's been wrong for quite
a long time, so back-patch to all supported branches.
Translation updates
Release notes for 9.3.4, 9.2.8, 9.1.13, 9.0.17, 8.4.21.
Stamp 8.4.21.
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.
Fix refcounting bug in PLy_modify_tuple().

We must increment the refcount on "plntup" as soon as we have the
reference, not sometime later.  Otherwise, if an error is thrown in
between, the Py_XDECREF(plntup) call in the PG_CATCH block removes a
refcount we didn't add, allowing the object to be freed even though
it's still part of the plpython function's parsetree.

This appears to be the cause of crashes seen on buildfarm member
prairiedog.  It's a bit surprising that we've not seen it fail repeatably
before, considering that the regression tests have been exercising the
faulty code path since 2009.

The real-world impact is probably minimal, since it's unlikely anyone would
be provoking the "TD["new"] is not a dictionary" error in production, and
that's the only case that is actually wrong.  Still, it's a bug affecting
the regression tests, so patch all supported branches.

In passing, remove dead variable "plstr", and demote "platt" to a local
variable inside the PG_TRY block, since we don't need to clean it up
in the PG_CATCH path.