pgsql: Replace static bufs with a StringInfo in cash_words()

Replace static bufs with a StringInfo in cash_words()

For clarity. The code was correct, and the buffer was large enough,
but string manipulation with no bounds checking is scary.

This incurs an extra palloc+pfree to every call, but in quick
performance testing, it doesn't seem to be significant.

Reviewed-by: Robert Haas
Discussion: https://www.postgresql.org/message-id/7f86e06a-98c5-4ce3-8ec9-3885c8de0358@iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5bf948d564e36553d2a1cda3244a52d054238af4

Modified Files
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src/backend/utils/adt/cash.c | 85 +++++++++++++++++++++++---------------------
1 file changed, 44 insertions(+), 41 deletions(-)