pgsql: Remove ReorderBufferTupleBuf structure.

Remove ReorderBufferTupleBuf structure.

Since commit a4ccc1cef, the 'node' and 'alloc_tuple_size' fields of
the ReorderBufferTupleBuf structure are no longer used. This leaves
only the 'tuple' field in the structure. Since keeping a single-field
structure makes little sense, the ReorderBufferTupleBuf is removed
entirely. The code is refactored accordingly.

No back-patching since these are ABI changes in an exposed structure
and functions, and there would be some risk of breaking extensions.

Author: Aleksander Alekseev
Reviewed-by: Amit Kapila, Masahiko Sawada, Reid Thompson
Discussion: https://postgr.es/m/CAD21AoCvnuxiXXfRecp7g9+CeC35POQfhuQeJFr7_9u_Q5jc_Q@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/08e6344fd6423210b339e92c069bb979ba4e7cd6

Modified Files
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contrib/test_decoding/test_decoding.c | 8 +--
src/backend/replication/logical/decode.c | 26 ++++----
src/backend/replication/logical/reorderbuffer.c | 89 ++++++++++++-------------
src/backend/replication/pgoutput/pgoutput.c | 4 +-
src/include/replication/reorderbuffer.h | 31 ++-------
src/tools/pgindent/typedefs.list | 1 -
6 files changed, 68 insertions(+), 91 deletions(-)