pgsql: Mark ParallelMessagePending as sig_atomic_t

Mark ParallelMessagePending as sig_atomic_t

ParallelMessagePending was previously marked as a boolean which should
be fine on modern platforms, but the C standard recommends the use of
sig_atomic_t for variables manipulated in signal handlers.

Author: Hayato Kuroda
Discussion: /messages/by-id/TYAPR01MB58667C15A95A234720F4F876F5529@TYAPR01MB5866.jpnprd01.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/78fdb1e50f7fd394505a400b507f70ecffa6d7bf

Modified Files
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src/backend/access/transam/parallel.c | 2 +-
src/include/access/parallel.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)