pgsql: Fix poll() implementation of WaitLatchOrSocket to notice postmas

Fix poll() implementation of WaitLatchOrSocket to notice postmaster death.

When the remote end of the pipe is closed, select() reports the fd as
readable, but poll() has a separate POLLHUP return code for that.

Spotted by Peter Geoghegan.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/b2b4af535eb733ba0c2ea6eeb2b14cac7f1ca4be

Modified Files
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src/backend/port/unix_latch.c |    7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)