Fix #8799: BUGCHECK "decompression overran buffer (179)" when WITH LOCK clause is used (#8803)

VIO_writelock creates new_rpb by copying from org_rpb which has rpb_delta flag set. new_rpb is passed to prepare_update. It creates a delta but its size exceeds the limit (1024) so the current version is stored as a regular record. The problem is that rpb_delta flag remains set for new_rpb, and then replace_record sets it in the header of the primary version. From this moment any attempt to get data of older versions fails.

Author: ilya071294

src/jrd/vio.cpp

@@ -5640,6 +5640,8 @@ static int prepare_update(	thread_db*		tdbb,
 	UCHAR differences[MAX_DIFFERENCES];
 	if (new_rpb)
 	{
+		new_rpb->rpb_flags &= ~rpb_delta;
+
 		// If both descriptors share the same record, there cannot be any difference.
 		// This trick is used by VIO_writelock(), but can be a regular practice as well.
 		if (new_rpb->rpb_address == temp->rpb_address)