Fix potential data corruption during freeze

Fix oversight in 3b97e6823b bug fix. Bitwise AND is used instead of OR and
it cleans all bits in t_infomask heap tuple field.

Backpatch to 9.3

src/backend/access/heap/heapam.c

@@ -6627,7 +6627,7 @@ heap_prepare_freeze_tuple(HeapTupleHeader tuple, TransactionId cutoff_xid,
 			frz->t_infomask &= ~HEAP_XMAX_BITS;
 			frz->xmax = newxmax;
 			if (flags & FRM_MARK_COMMITTED)
-				frz->t_infomask &= HEAP_XMAX_COMMITTED;
+				frz->t_infomask |= HEAP_XMAX_COMMITTED;
 			changed = true;
 			totally_frozen = false;
 		}