pgsql: Fix wrong logic in TransactionIdInRecentPast()

Fix wrong logic in TransactionIdInRecentPast()

The TransactionIdInRecentPast() should return false for all the transactions
older than TransamVariables->oldestClogXid. However, the function contains
a bug in comparison FullTransactionId to TransactionID allowing full
transactions between nextXid - 2^32 and oldestClogXid - 2^31.

This commit fixes TransactionIdInRecentPast() by turning the oldestClogXid into
FullTransactionId first, then performing the comparison.

Backpatch to all supported versions.

Reported-by: Egor Chindyaskin
Bug: 18212
Discussion: https://postgr.es/m/18212-547307f8adf57262%40postgresql.org
Author: Karina Litskevich
Reviewed-by: Kyotaro Horiguchi
Backpatch-through: 12

Branch
------
REL_13_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/4efaf4b09e8f9a9c8b04a6c82454c248de042119

Modified Files
--------------
src/backend/utils/adt/xid8funcs.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)