pgsql: Provide DSM segment to ExecXXXInitializeWorker functions.

Provide DSM segment to ExecXXXInitializeWorker functions.

Previously, executor nodes running in parallel worker processes didn't
have access to the dsm_segment object used for parallel execution. In
order to support resource management based on DSM segment lifetime,
they need that. So create a ParallelWorkerContext object to hold it
and pass it to all InitializeWorker functions.

Author: Thomas Munro
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=2W=cOkiZxcg6qiFQP-dHUe09aqTrEMM7yJDrHMhDv_RA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7082e614c0dd504cdf49c4d5a692159f22e78f9d

Modified Files
--------------
src/backend/executor/execParallel.c | 27 +++++++++++++++++----------
src/backend/executor/nodeBitmapHeapscan.c | 5 +++--
src/backend/executor/nodeCustom.c | 7 ++++---
src/backend/executor/nodeForeignscan.c | 7 ++++---
src/backend/executor/nodeIndexonlyscan.c | 5 +++--
src/backend/executor/nodeIndexscan.c | 5 +++--
src/backend/executor/nodeSeqscan.c | 5 +++--
src/backend/executor/nodeSort.c | 4 ++--
src/include/access/parallel.h | 6 ++++++
src/include/executor/nodeBitmapHeapscan.h | 2 +-
src/include/executor/nodeCustom.h | 2 +-
src/include/executor/nodeForeignscan.h | 2 +-
src/include/executor/nodeIndexonlyscan.h | 2 +-
src/include/executor/nodeIndexscan.h | 3 ++-
src/include/executor/nodeSeqscan.h | 3 ++-
src/include/executor/nodeSort.h | 2 +-
src/tools/pgindent/typedefs.list | 1 +
17 files changed, 55 insertions(+), 33 deletions(-)