pgsql: Add pg_xlogdump contrib program

Add pg_xlogdump contrib program

This program relies on rm_desc backend routines and the xlogreader
infrastructure to emit human-readable rendering of WAL records.

Author: Andres Freund, with many reworks by Álvaro
Reviewed (in a much earlier version) by Peter Eisentraut

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/639ed4e84b7493594860f56b78b25fd113e78fd7

Modified Files
--------------
contrib/pg_xlogdump/Makefile      |   32 ++
contrib/pg_xlogdump/compat.c      |   94 +++++
contrib/pg_xlogdump/pg_xlogdump.c |  711 +++++++++++++++++++++++++++++++++++++
contrib/pg_xlogdump/rmgrdesc.c    |   36 ++
contrib/pg_xlogdump/rmgrdesc.h    |   21 ++
doc/src/sgml/contrib.sgml         |    1 +
doc/src/sgml/filelist.sgml        |    1 +
doc/src/sgml/pg_xlogdump.sgml     |  205 +++++++++++
doc/src/sgml/ref/pg_isready.sgml  |    2 +-
src/include/utils/palloc.h        |    4 +-
10 files changed, 1104 insertions(+), 3 deletions(-)