pgsql: pg_rewind: Replace the hybrid list+array data structure with sim

pg_rewind: Replace the hybrid list+array data structure with simplehash.

Now that simplehash can be used in frontend code, let's make use of it.

Reviewed-by: Kyotaro Horiguchi, Soumyadeep Chakraborty
Discussion: https://www.postgresql.org/message-id/0c5b3783-af52-3ee5-f8fa-6e794061f70d%40iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f81e97d0475cd4bc597adc23b665bd84fbf79a0d

Modified Files
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src/bin/pg_rewind/copy_fetch.c  |   4 +-
src/bin/pg_rewind/fetch.c       |   2 +-
src/bin/pg_rewind/fetch.h       |   2 +-
src/bin/pg_rewind/filemap.c     | 294 ++++++++++++++++++----------------------
src/bin/pg_rewind/filemap.h     |  67 ++++-----
src/bin/pg_rewind/libpq_fetch.c |   4 +-
src/bin/pg_rewind/pg_rewind.c   |  14 +-
7 files changed, 176 insertions(+), 211 deletions(-)