Partial fix for dropped columns in functions returning composite.

When a view has a function-returning-composite in FROM, and there are
some dropped columns in the underlying composite type, ruleutils.c
printed junk in the column alias list for the reconstructed FROM entry.
Before 9.3, this was prevented by doing get_rte_attribute_is_dropped
tests while printing the column alias list; but that solution is not
currently available to us for reasons I'll explain below.  Instead,
check for empty-string entries in the alias list, which can only exist
if that column position had been dropped at the time the view was made.
(The parser fills in empty strings to preserve the invariant that the
aliases correspond to physical column positions.)

While this is sufficient to handle the case of columns dropped before
the view was made, we have still got issues with columns dropped after
the view was made.  In particular, the view could contain Vars that
explicitly reference such columns!  The dependency machinery really
ought to refuse the column drop attempt in such cases, as it would do
when trying to drop a table column that's explicitly referenced in
views.  However, we currently neglect to store dependencies on columns
of composite types, and fixing that is likely to be too big to be
back-patchable (not to mention that existing views in existing databases
would not have the needed pg_depend entries anyway).  So I'll leave that
for a separate patch.

Pre-9.3, ruleutils would print such Vars normally (with their original
column names) even though it suppressed their entries in the RTE's
column alias list.  This is certainly bogus, since the printed view
definition would fail to reload, but at least it didn't crash.  However,
as of 9.3 the printed column alias list is tightly tied to the names
printed for Vars; so we can't treat columns as dropped for one purpose
and not dropped for the other.  This is why we can't just put back the
get_rte_attribute_is_dropped test: it results in an assertion failure
if the view in fact contains any Vars referencing the dropped column.
Once we've got dependencies preventing such cases, we'll probably want
to do it that way instead of relying on the empty-string test used here.

This fix turned up a very ancient bug in outfuncs/readfuncs, namely
that T_String nodes containing empty strings were not dumped/reloaded
correctly: the node was printed as "<>" which is read as a string
value of <>.  Since (per SQL) we disallow empty-string identifiers,
such nodes don't occur normally, which is why we'd not noticed.
(Such nodes aren't used for literal constants, just identifiers.)

Per report from Marc Schablewski.  Back-patch to 9.3 which is where
the rule printing behavior changed.  The dangling-variable case is
broken all the way back, but that's not what his complaint is about.
Update time zone data files to tzdata release 2014e.

DST law changes in Crimea, Egypt, Morocco.  New zone Antarctica/Troll
for Norwegian base in Queen Maud Land.
Fix xreflabel for hot_standby_feedback.

Rather remarkable that this has been wrong since 9.1 and nobody noticed.
First-draft release notes for 9.3.5.

As usual, the release notes for older branches will be made by cutting
these down, but put them up for community review first.

Note: a few of these items actually don't apply to 9.3, but only to older
branches.  I'll sort that out when copying the text into the older
release-X.Y.sgml files.
Replace "internationalize" with "localize" where appropriate
Update SQL features list
Translation updates
Properly use DEFAULT_EVENT_SOURCE in pgevent.c

This was broken and reverted in a previous commit. The (this time verified)
fix is to simly add postgres_fe.h.

MauMau, review by Amit Kapila
Defend against bad relfrozenxid/relminmxid/datfrozenxid/datminmxid values.

In commit a61daa14d56867e90dc011bbba52ef771cea6770, we fixed pg_upgrade so
that it would install sane relminmxid and datminmxid values, but that does
not cure the problem for installations that were already pg_upgraded to
9.3; they'll initially have "1" in those fields.  This is not a big problem
so long as 1 is "in the past" compared to the current nextMultiXact
counter.  But if an installation were more than halfway to the MXID wrap
point at the time of upgrade, 1 would appear to be "in the future" and
that would effectively disable tracking of oldest MXIDs in those
tables/databases, until such time as the counter wrapped around.

While in itself this isn't worse than the situation pre-9.3, where we did
not manage MXID wraparound risk at all, the consequences of premature
truncation of pg_multixact are worse now; so we ought to make some effort
to cope with this.  We discussed advising users to fix the tracking values
manually, but that seems both very tedious and very error-prone.

Instead, this patch adopts two amelioration rules.  First, a relminmxid
value that is "in the future" is allowed to be overwritten with a
full-table VACUUM's actual freeze cutoff, ignoring the normal rule that
relminmxid should never go backwards.  (This essentially assumes that we
have enough defenses in place that wraparound can never occur anymore,
and thus that a value "in the future" must be corrupt.)  Second, if we see
any "in the future" values then we refrain from truncating pg_clog and
pg_multixact.  This prevents loss of clog data until we have cleaned up
all the broken tracking data.  In the worst case that could result in
considerable clog bloat, but in practice we expect that relfrozenxid-driven
freezing will happen soon enough to fix the problem before clog bloat
becomes intolerable.  (Users could do manual VACUUM FREEZEs if not.)

Note that this mechanism cannot save us if there are already-wrapped or
already-truncated-away MXIDs in the table; it's only capable of dealing
with corrupt tracking values.  But that's the situation we have with the
pg_upgrade bug.

For consistency, apply the same rules to relfrozenxid/datfrozenxid.  There
are not known mechanisms for these to get messed up, but if they were, the
same tactics seem appropriate for fixing them.
Adjust cutoff points in newly-added sanity tests.

Per recommendation from Andres.
Release notes for 9.3.5, 9.2.9, 9.1.14, 9.0.18, 8.4.22.
Merge remote-tracking branch 'origin/master' into rollups_branch