Remove unnecessary segment number calculation after wal_removed invalidation of replication slots

Hi,

It looks like there's an unnecessary segment number calculation after
InvalidateObsoleteReplicationSlots in CreateCheckPoint and
CreateRestartPoint. Since none of RedoRecPtr, _logSegNo and
wal_segment_size are changed by the slot invalidation code [1], the
recalculation of
_logSegNo with XLByteToSeg seems unnecessary.

I've attached a patch to fix this.

[1] Assertions like the following won't fail with make check-world
proving InvalidateObsoleteReplicationSlots doesn't change them at all.

XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size);
KeepLogSeg(recptr, &_logSegNo);
+ _logSegNo_saved = _logSegNo;
+ RedoRecPtr_saved = RedoRecPtr;
if (InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_REMOVED,

_logSegNo, InvalidOid,

InvalidTransactionId))
{
+ Assert(_logSegNo_saved == _logSegNo);
+ Assert(RedoRecPtr_saved == RedoRecPtr);

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com