Fix an O(N^2) performance issue for sessions modifying many relations.

AtEOXact_RelationCache() scanned the entire relation cache at the end of
any transaction that created a new relation or assigned a new relfilenode.
Thus, clients such as pg_restore had an O(N^2) performance problem that
would start to be noticeable after creating 10000 or so tables.  Since
typically only a small number of relcache entries need any cleanup, we
can fix this by keeping a small list of their OIDs and doing hash_searches
for them.  We fall back to the full-table scan if the list overflows.

Ideally, the maximum list length would be set at the point where N
hash_searches would cost just less than the full-table scan.  Some quick
experimentation says that point might be around 50-100; I (tgl)
conservatively set MAX_EOXACT_LIST = 32.  For the case that we're worried
about here, which is short single-statement transactions, it's unlikely
there would ever be more than about a dozen list entries anyway; so it's
probably not worth being too tense about the value.

We could avoid the hash_searches by instead keeping the target relcache
entries linked into a list, but that would be noticeably more complicated
and bug-prone because of the need to maintain such a list in the face of
relcache entry drops.  Since a relcache entry can only need such cleanup
after a somewhat-heavyweight filesystem operation, trying to save a
hash_search per cleanup doesn't seem very useful anyway --- it's the scan
over all the not-needing-cleanup entries that we wish to avoid here.

Jeff Janes, reviewed and tweaked a bit by Tom Lane
WIP for MVs: Minor rearrangement of refreshMatViewData() for consistency.
doc: Fix syntax of a URL

Leading white space before the "http:" is apparently treated as a
relative link at least by some browsers.
Fix error-checking typo in check_TSCurrentConfig().

The code failed to detect an out-of-memory failure.

Xi Wang
Fix one-byte buffer overrun in PQprintTuples().

This bug goes back to the original Postgres95 sources.  Its significance
to modern PG versions is marginal, since we have not used PQprintTuples()
internally in a very long time, and it doesn't seem to have ever been
documented either.  Still, it *is* exposed to client apps, so somebody
out there might possibly be using it.

Xi Wang
Refactor ALTER some-obj RENAME implementation

Remove duplicate implementations of catalog munging and miscellaneous
privilege checks.  Instead rely on already existing data in
objectaddress.c to do the work.

Author: KaiGai Kohei, changes by me
Reviewed by: Robert Haas, Álvaro Herrera, Dimitri Fontaine
Add ddl_command_end support for event triggers.

Dimitri Fontaine, with slight changes by me
Add infrastructure for storing a VARIADIC ANY function's VARIADIC flag.

Originally we didn't bother to mark FuncExprs with any indication whether
VARIADIC had been given in the source text, because there didn't seem to be
any need for it at runtime.  However, because we cannot fold a VARIADIC ANY
function's arguments into an array (since they're not necessarily all the
same type), we do actually need that information at runtime if VARIADIC ANY
functions are to respond unsurprisingly to use of the VARIADIC keyword.
Add the missing field, and also fix ruleutils.c so that VARIADIC ANY
function calls are dumped properly.

Extracted from a larger patch that also fixes concat() and format() (the
only two extant VARIADIC ANY functions) to behave properly when VARIADIC is
specified.  This portion seems appropriate to review and commit separately.

Pavel Stehule
Typo fixes.

Noted by Thom Brown.
WIP for MVs: partial work on pg_dump dependencies.
Merge branch 'master' into matview