pgsql: Fix parallel safety markings for pg_start_backup.

Fix parallel safety markings for pg_start_backup.

Commit 7117685461af50f50c03f43e6a622284c8d54694 made pg_start_backup
parallel-restricted rather than parallel-safe, because it now relies
on backend-private state that won't be synchronized with the parallel
worker. However, it didn't update pg_proc.h. Separately, Andreas
Karlsson observed that system_views.sql neglected to reiterate the
parallel-safety markings whe redefining various functions, including
this one; so add a PARALLEL RESTRICTED declaration there to match
the new value in pg_proc.h.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/37d0c2cb1ab2d3da0cb9a6388450776fc31c16ee

Modified Files
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src/backend/catalog/system_views.sql | 3 ++-
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.h | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)