pgsql: Fix memory leak with lower,upper and initcap with ICU-provided

pgsql: Fix memory leak with lower,upper and initcap with ICU-provided

Fix memory leak with lower, upper and initcap with ICU-provided collations

The leak happens in str_tolower, str_toupper and str_initcap, which are
used in several places including their equivalent SQL-level functions,
and can only be triggered when using an ICU-provided collation when
converting the input string.

b615920 fixed a similar leak.  Backpatch down 10 where ICU collations
have been introduced.

Author: Konstantin Knizhnik
Discussion: https://postgr.es/m/94c0ad0a-cbc2-e4a3-7829-2bdeaf9146db@postgrespro.ru
Backpatch-through: 10

Branch
------
REL_10_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/604d20679e20c72a36ba267e67bec356a79d8448

Modified Files
--------------
src/backend/utils/adt/formatting.c | 3 +++
1 file changed, 3 insertions(+)