pgsql: Add repalloc0 and repalloc0_array

Add repalloc0 and repalloc0_array

These zero out the space added by repalloc. This is a common pattern
that is quite hairy to code by hand.

Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://www.postgresql.org/message-id/b66dfc89-9365-cb57-4e1f-b7d31813eeec@enterprisedb.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b4b7ce8061d34cea2b4915c41403b2a74d5fde0e

Modified Files
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src/backend/executor/nodeHash.c | 8 ++------
src/backend/libpq/be-fsstubs.c | 9 +++------
src/backend/optimizer/util/placeholder.c | 13 ++++---------
src/backend/optimizer/util/relnode.c | 29 ++++++++---------------------
src/backend/parser/parse_param.c | 10 +++-------
src/backend/storage/lmgr/lwlock.c | 9 ++-------
src/backend/utils/adt/ruleutils.c | 9 ++-------
src/backend/utils/cache/typcache.c | 10 ++--------
src/backend/utils/mmgr/mcxt.c | 20 ++++++++++++++++++++
src/include/utils/palloc.h | 2 ++
10 files changed, 48 insertions(+), 71 deletions(-)