Allow units to be specified in relation option setting value.

This introduces an infrastructure which allows us to specify the units
like ms (milliseconds) in integer relation option, like GUC parameter.
Currently only autovacuum_vacuum_cost_delay reloption can accept
the units.

Reviewed by Michael Paquier
Allow escaping of option values for options passed at connection start.

This is useful to allow to set GUCs to values that include spaces;
something that wasn't previously possible. The primary case motivating
this is the desire to set default_transaction_isolation to 'repeatable
read' on a per connection basis, but other usecases like seach_path do
also exist.

This introduces a slight backward incompatibility: Previously a \ in
an option value would have been passed on literally, now it'll be
taken as an escape.

The relevant mailing list discussion starts with
20140204125823.GJ12016@awork2.anarazel.de.
Revert "Allow units to be specified in relation option setting value."

This reverts commit e23014f3d40f7d2c23bc97207fd28efbe5ba102b.

As the side effect of the reverted commit, when the unit is
specified, the reloption was stored in the catalog with the unit.
This broke pg_dump (specifically, it prevented pg_dump from
outputting restorable backup regarding the reloption) and
turned the buildfarm red. Revert the commit until the fixed
version is ready.
Fix citext upgrade script for disallowance of oidvector element assignment.

In commit 45e02e3232ac7cc5ffe36f7986159b5e0b1f6fdc, we intentionally
disallowed updates on individual elements of oidvector columns.  While that
still seems like a sane idea in the abstract, we (I) forgot that citext's
"upgrade from unpackaged" script did in fact perform exactly such updates,
in order to fix the problem that citext indexes should have a collation
but would not in databases dumped or upgraded from pre-9.1 installations.

Even if we wanted to add casts to allow such updates, there's no practical
way to do so in the back branches, so the only real alternative is to make
citext's kluge even klugier.  In this patch, I cast the oidvector to text,
fix its contents with regexp_replace, and cast back to oidvector.  (Ugh!)

Since the aforementioned commit went into all active branches, we have to
fix this in all branches that contain the now-broken update script.

Per report from Eric Malm.
Always use our getaddrinfo.c on Windows.

Commit a16bac36eca8158cbf78987e95376f610095f792 let "configure" detect
the system getaddrinfo() when building under 64-bit MinGW-w64.  However,
src/include/port/win32/sys/socket.h assumes all native Windows
configurations use our replacement.  This change placates buildfarm
member jacana until we establish a plan for getaddrinfo() on Windows.
Add min and max aggregates for inet/cidr data types.

Haribabu Kommi, reviewed by Muhammad Asif Naeem
doc: Revert ALTER TABLESPACE summary line

It was changed when ALTER TABLESPACE / MOVE was added but then not
updated when that was moved back out.
Assorted message improvements
Fix bug in compressed GIN data leaf page splitting code.

The list of posting lists it's dealing with can contain placeholders for
deleted posting lists. The placeholders are kept around so that they can
be WAL-logged, but we must be careful to not try to access them.

This fixes bug #11280, reported by Mårten Svantesson. Backpatch to 9.4,
where the compressed data leaf page code was added.
pg_is_xlog_replay_paused():  remove super-user-only restriction

Also update docs to mention which function are super-user-only.

Report by sys-milan@statpro.com

Backpatch through 9.4
Update C comment for pg_attribute.attislocal

Indicates if column has ever been local/non-inherited
Make backend local tracking of buffer pins memory efficient.

Since the dawn of time (aka Postgres95) multiple pins of the same
buffer by one backend have been optimized not to modify the shared
refcount more than once. This optimization has always used a NBuffer
sized array in each backend keeping track of a backend's pins.

That array (PrivateRefCount) was one of the biggest per-backend memory
allocations, depending on the shared_buffers setting. Besides the
waste of memory it also has proven to be a performance bottleneck when
assertions are enabled as we make sure that there's no remaining pins
left at the end of transactions. Also, on servers with lots of memory
and a correspondingly high shared_buffers setting the amount of random
memory accesses can also lead to poor cpu cache efficiency.

Because of these reasons a backend's buffers pins are now kept track
of in a small statically sized array that overflows into a hash table
when necessary. Benchmarks have shown neutral to positive performance
results with considerably lower memory usage.

Patch by me, review by Robert Haas.

Discussion: 20140321182231.GA17111@alap3.anarazel.de
Again update C comments for pg_attribute.attislocal
doc: Various typo/grammar fixes

Errors detected using Topy (https://github.com/intgr/topy), all
changes verified by hand and some manual tweaks added.

Marti Raudsepp

Individual changes backpatched, where applicable, as far as 9.0.