pgsql: Replace formatting.c's fixed-size output buffers with StringInfo

Replace formatting.c's fixed-size output buffers with StringInfos.

In both versions of NUM_processor(), use a StringInfo for the
output string, eliminating the need to guess an upper bound
for the output length, and removing the need to truncate some
strings of unpredictable length.

Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Discussion: https://postgr.es/m/3451175.1786641871@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ec352b37d88a12f0256526ff0a51bd86d587d604

Modified Files
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src/backend/utils/adt/formatting.c | 310 +++++++++++++++----------------------
1 file changed, 127 insertions(+), 183 deletions(-)