pgsql: heapam: Pass number of required pages to RelationGetBufferForTup

heapam: Pass number of required pages to RelationGetBufferForTuple()

A future commit will use this information to determine how aggressively to
extend the relation by. In heap_multi_insert() we know accurately how many
pages we need once we need to extend the relation, providing an accurate lower
bound for how much to extend.

Reviewed-by: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Discussion: https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5279e9db8e8da3c310c0068da2de98df5a714b2e

Modified Files
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src/backend/access/heap/heapam.c | 58 +++++++++++++++++++++++++++++++++++++---
src/backend/access/heap/hio.c | 8 +++++-
src/include/access/hio.h | 3 ++-
3 files changed, 63 insertions(+), 6 deletions(-)