pgsql: Add missing initializations of p_perminfo

Add missing initializations of p_perminfo

In a61b1f74823, we failed to update transformFromClauseItem() and
buildNSItemFromLists() to set ParseNamespaceItem.p_perminfo causing
it to point to garbage.

Pointed out by Tom Lane.

Reported-by: Farias de Oliveira <matheusfarias519@gmail.com>
Discussion: https://postgr.es/m/3173476.1689286373%40sss.pgh.pa.us
Backpatch-through: 16

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/4a7301c7ad1c504c5a3f485a1d28cfd62b3ecbb0

Modified Files
--------------
src/backend/parser/parse_clause.c   | 1 +
src/backend/parser/parse_relation.c | 1 +
2 files changed, 2 insertions(+)