pgsql: Remove spclocation field from pg_tablespace

Remove spclocation field from pg_tablespace

Instead, add a function pg_tablespace_location(oid) used to return
the same information, and do this by reading the symbolic link.

Doing it this way makes it possible to relocate a tablespace when the
database is down by simply changing the symbolic link.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/16d8e594acd96661267cb7897834f9cba51a2ffd

Modified Files
--------------
contrib/pg_upgrade/info.c | 25 +++++++++++++++-------
contrib/pg_upgrade/tablespace.c | 18 ++++++++++-----
doc/src/sgml/catalogs.sgml | 7 ------
doc/src/sgml/func.sgml | 9 ++++++++
doc/src/sgml/xaggr.sgml | 4 +-
src/backend/commands/tablespace.c | 2 -
src/backend/utils/adt/misc.c | 39 +++++++++++++++++++++++++++++++++++
src/bin/pg_dump/pg_dumpall.c | 11 +++++++++-
src/bin/psql/describe.c | 23 ++++++++++++++------
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.h | 3 ++
src/include/catalog/pg_tablespace.h | 12 ++++------
src/include/utils/builtins.h | 1 +
13 files changed, 115 insertions(+), 41 deletions(-)