pgsql: Use palloc_array() in pltcl and plperl to avoid overflow

Use palloc_array() in pltcl and plperl to avoid overflow

Some of these could overflow on 32-bit systems with the right input.
Convert all cases where we called palloc() with multiplication to fix
them. Not all of them were bugs, but it's better to be safe than
sorry.

Reported-by: Tulya Project, Team Dhiutsa, Bitecope Technologies Private Ltd
Backpatch-through: 14
Security: CVE-2026-14677

Branch
------
REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/b56cc7deb9af972226f7d6259248e00eb124069f
Author: Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi>

Modified Files
--------------
src/pl/plperl/SPI.xs | 6 +++---
src/pl/plperl/plperl.c | 38 +++++++++++++++++++-------------------
src/pl/tcl/pltcl.c | 20 ++++++++++----------
3 files changed, 32 insertions(+), 32 deletions(-)