pgsql: Report catalog_xmin separately in hot_standby_feedback

Report catalog_xmin separately in hot_standby_feedback

If the upstream walsender is using a physical replication slot, store the
catalog_xmin in the slot's catalog_xmin field. If the upstream doesn't use a
slot and has only a PGPROC entry behaviour doesn't change, as we store the
combined xmin and catalog_xmin in the PGPROC entry.

Author: Craig Ringer

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/5737c12df0581b3298e3e9586bdef170811ce176

Modified Files
--------------
doc/src/sgml/protocol.sgml                         |  33 ++++++-
src/backend/replication/walreceiver.c              |  43 ++++++--
src/backend/replication/walsender.c                | 108 +++++++++++++++------
src/backend/storage/ipc/procarray.c                |  12 ++-
src/include/storage/proc.h                         |   5 +
src/include/storage/procarray.h                    |  11 +++
.../recovery/t/010_logical_decoding_timelines.pl   |  38 +++++++-
7 files changed, 199 insertions(+), 51 deletions(-)