pgsql: Setup error context callback for transaction lock waits

Setup error context callback for transaction lock waits

With this in place, a session blocking behind another one because of
tuple locks will get a context line mentioning the relation name, tuple
TID, and operation being done on tuple.  For example:

LOG:  process 11367 still waiting for ShareLock on transaction 717 after 1000.108 ms
DETAIL:  Process holding the lock: 11366. Wait queue: 11367.
CONTEXT:  while updating tuple (0,2) in relation "foo"
STATEMENT:  UPDATE foo SET value = 3;

Most usefully, the new line is displayed by log entries due to
log_lock_waits, although of course it will be printed by any other log
message as well.

Author: Christian Kruse, some tweaks by Álvaro Herrera
Reviewed-by: Amit Kapila, Andres Freund, Tom Lane, Robert Haas

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/f88d4cfc9d417dac2ee41a8f5e593898e56fd2bd

Modified Files
--------------
src/backend/access/heap/heapam.c            |   80 ++++++++++++++-------
src/backend/access/nbtree/nbtinsert.c       |    2 +-
src/backend/catalog/index.c                 |    8 ++-
src/backend/executor/execMain.c             |    4 +-
src/backend/executor/execUtils.c            |    3 +-
src/backend/replication/logical/snapbuild.c |    2 +-
src/backend/storage/lmgr/lmgr.c             |  102 ++++++++++++++++++++++++++-
src/include/storage/lmgr.h                  |   17 ++++-
src/nls-global.mk                           |    5 +-
9 files changed, 189 insertions(+), 34 deletions(-)