pgsql: Allow external recovery_config_directory

Allow external recovery_config_directory
If required, recovery.conf can now be located outside of the data directory.
Server needs read/write permissions on this directory.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/bc5334d8679c428a709d150666b288171795bd76

Modified Files
--------------
doc/src/sgml/config.sgml          |   17 +++++++++++++++++
src/backend/access/transam/xlog.c |   18 +++++++++++-------
src/backend/utils/init/globals.c  |    1 +
src/backend/utils/init/miscinit.c |   19 +++++++++++++++++++
src/backend/utils/misc/guc.c      |   24 ++++++++++++++++++++++++
src/include/miscadmin.h           |    2 ++
src/include/utils/guc.h           |    1 +
7 files changed, 75 insertions(+), 7 deletions(-)