pgsql: Fix incorrect initialization of BackendActivityBuffer.

Fix incorrect initialization of BackendActivityBuffer.

Since commit c8e8b5a6e, this has been zeroed out using the wrong length.
In practice the length would always be too small, leading to not zeroing
the whole buffer rather than clobbering additional memory; and that's
pretty harmless, both because shmem would likely start out as zeroes
and because we'd reinitialize any given entry before use.  Still,
it's bogus, so fix it.

Reported by Petru-Florin Mihancea (bug #15312)

Discussion: https://postgr.es/m/153363913073.1303.6518849192351268091@wrigleys.postgresql.org

Branch
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REL9_3_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6be25d52cfbe8d43426721591513ae3725b7da6f

Modified Files
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src/backend/postmaster/pgstat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)