pgsql: Allow redeclaration of typedef yyscan_t

Allow redeclaration of typedef yyscan_t

This is allowed in C11, so we don't need the workaround guards against
it anymore.  This effectively reverts commit 382092a0cd2 that put
these guards in place.

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/10d32190-f31b-40a5-b177-11db55597355@eisentraut.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ae0e1be9f2a20f6b64072dcee5b8dd7b9027a8fa

Modified Files
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contrib/cube/cubedata.h                     | 3 ---
contrib/seg/segdata.h                       | 3 ---
src/backend/utils/adt/jsonpath_internal.h   | 3 ---
src/bin/pgbench/pgbench.h                   | 3 ---
src/include/bootstrap/bootstrap.h           | 3 ---
src/include/fe_utils/psqlscan_int.h         | 6 ------
src/include/replication/syncrep.h           | 3 ---
src/include/replication/walsender_private.h | 3 ---
src/pl/plpgsql/src/plpgsql.h                | 3 ---
9 files changed, 30 deletions(-)