pgsql: Fix logic to detect conflicts or blocks involving exclusive locks

Log Message:
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Fix logic to detect conflicts or blocks involving exclusive locks in parallel restore items.
If a currently running item needs an exclusive lock on any item that the candidate items needs
any sort of lock on, or vice versa, then the candidate item is not allowed to run now, and
must wait till later.

Modified Files:
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pgsql/src/bin/pg_dump:
pg_backup_archiver.c (r1.169 -> r1.170)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_backup_archiver.c?r1=1.169&r2=1.170)