pgsql: pg_upgrade: Fix inconsistency in memory freeing

pg_upgrade: Fix inconsistency in memory freeing

The function in charge of freeing the memory from a result created by
PQescapeIdentifier() has to be PQfreemem(), to ensure that both
allocation and free come from libpq.

One spot in pg_upgrade was not respecting that for pg_database's
datlocale (daticulocale in v16) when the collation provider is libc (aka
datlocale/daticulocale is NULL) with an allocation done using
pg_strdup() and a free with PQfreemem(). The code is changed to always
use PQescapeLiteral() when processing the input.

Oversight in 9637badd9f92. This commit is similar to 48e4ae9a0707 and
5b94e2753439.

Author: Michael Paquier <michael(at)paquier(dot)xyz>
Co-authored-by: Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
Discussion: https://postgr.es/m/Z601RQxTmIUohdkV@paquier.xyz
Backpatch-through: 16

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/9ca2145b00fb5d6272e87f274b0f40df77d81a51

Modified Files
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src/bin/pg_upgrade/pg_upgrade.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)