pgsql: Use pg_memory_is_all_zeros() in pgstatfuncs.c.

Use pg_memory_is_all_zeros() in pgstatfuncs.c.

There are a few places in this file that use memset() and memcmp()
to determine whether a section of memory is all zeros. This commit
modifies them to use pg_memory_is_all_zeros() instead. These
aren't expected to be hot code paths, but this may optimize them a
bit. Plus, this allows us to remove some variables that were only
needed for the memset() and memcmp().

Author: Bertrand Drouvot
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/Z1hNubHfvMxlW6eu%40ip-10-97-1-34.eu-west-3.compute.internal

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e8d59294282bd01bc06f2af13c79b9155024a917

Modified Files
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src/backend/utils/adt/pgstatfuncs.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)