pgsql: Make pg_recievexlog by default loop on connection failures

Make pg_recievexlog by default loop on connection failures

Avoids the need for an external script in the most common
scenario. Behavior can be overridden using the -n/--noloop
commandline parameter.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/16282ae688de2b320cf176e9be8a89e4dfc60698

Modified Files
--------------
doc/src/sgml/ref/pg_receivexlog.sgml   |   19 +++++++++++++++
src/bin/pg_basebackup/pg_basebackup.c  |    6 +++++
src/bin/pg_basebackup/pg_receivexlog.c |   39 +++++++++++++++++++++++++++++--
src/bin/pg_basebackup/streamutil.c     |    7 +++++-
4 files changed, 67 insertions(+), 4 deletions(-)