Add the TK_IF_NULL_ROW opcode to deal with non-NULL result columns in the

result set of a view or subquery on the RHS of a LEFT JOIN that gets flattened.

FossilOrigin-Name: 3a5860d86fadcf924316707918bf283d26c53b1473e5e67f5cff59d18c2a7742

src/where.c

@@ -4976,6 +4976,8 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
         }else if( pOp->opcode==OP_Rowid ){
           pOp->p1 = pLevel->iIdxCur;
           pOp->opcode = OP_IdxRowid;
+        }else if( pOp->opcode==OP_IfNullRow ){
+          pOp->p1 = pLevel->iIdxCur;
         }
       }
     }