pgsql: Add new system view, pg_config

Add new system view, pg_config

Move and refactor the underlying code for the pg_config client
application to src/common in support of sharing it with a new
system information SRF called pg_config() which makes the same
information available via SQL. Additionally wrap the SRF with a
new system view, as called pg_config.

Patch by me with extensive input and review by Michael Paquier
and additional review by Alvaro Herrera.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/a5c43b886942e96ec5c745041f2d6a50c3205147

Modified Files
--------------
doc/src/sgml/catalogs.sgml | 52 +++++
src/backend/catalog/system_views.sql | 6 +
src/backend/utils/misc/Makefile | 4 +-
src/backend/utils/misc/pg_config.c | 103 +++++++++
src/bin/pg_config/Makefile | 14 --
src/bin/pg_config/pg_config.c | 429 ++++-------------------------------
src/common/Makefile | 19 +-
src/common/config_info.c | 206 +++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.h | 4 +
src/include/common/config_info.h | 21 ++
src/include/port.h | 1 +
src/include/utils/builtins.h | 3 +
src/port/path.c | 30 +++
src/test/regress/expected/rules.out | 3 +
src/tools/msvc/Mkvcbuild.pm | 4 +-
16 files changed, 491 insertions(+), 410 deletions(-)