pgsql: Ensure walsenders can be SIGTERMed while in non-walsender code

Ensure walsenders can be SIGTERMed while in non-walsender code

In oder to exit on SIGTERM when in non-walsender code,
such as do_pg_stop_backup(), we need to set the interrupt
variables that are used there, and not just the walsender
local ones.

Branch
------
REL9_1_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/5df22bba644d1c083118942292097ba2395fad15

Modified Files
--------------
src/backend/replication/walsender.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)