pgsql: Fix syslogger to not fail when log_rotation_age exceeds 2^31 mil

Fix syslogger to not fail when log_rotation_age exceeds 2^31 milliseconds.

We need to avoid calling WaitLatch with timeouts exceeding INT_MAX.
Fortunately a simple clamp will do the trick, since no harm is done if
the wait times out before it's really time to rotate the log file.
Per bug #7670 (probably bug #7545 is the same thing, too).

In passing, fix bogus definition of log_rotation_age's maximum value in
guc.c --- it was numerically right, but only because MINS_PER_HOUR and
SECS_PER_MINUTE have the same value.

Back-patch to 9.2. Before that, syslogger wasn't using WaitLatch.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/d038966ddb918872700f9f21affbc84d6bc2c029

Modified Files
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src/backend/postmaster/syslogger.c | 17 +++++++++++++++--
src/backend/utils/misc/guc.c | 2 +-
2 files changed, 16 insertions(+), 3 deletions(-)