pgsql: Change the signature of dynahash's alloc function

Change the signature of dynahash's alloc function

Instead of passing the current memory context to the alloc function
via a shared variable, pass it directly as an argument.

Reviewed-by: Tomas Vondra <tomas(at)vondra(dot)me>
Discussion: https://www.postgresql.org/message-id/01ab1d41-3eda-4705-8bbd-af898f5007f1@iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7b424e3108e4745ba7d37e358a1177911fa5a5ad

Modified Files
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src/backend/storage/ipc/shmem.c | 16 ++++++++++--
src/backend/utils/hash/dynahash.c | 52 ++++++++++++++++++++-------------------
src/include/utils/hsearch.h | 8 +++---
3 files changed, 45 insertions(+), 31 deletions(-)