Omit a pointless OP_Null when processing a value-list RHS of an IN operator
where the LHS is a rowid.

FossilOrigin-Name: 1361450a9dfe9476e8df98f370a3695752252245
diff --git a/src/expr.c b/src/expr.c
index 94647e5..aa55ff7 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1801,7 +1801,7 @@
         /* Loop through each expression in <exprlist>. */
         r1 = sqlite3GetTempReg(pParse);
         r2 = sqlite3GetTempReg(pParse);
-        sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
+        if( isRowid ) sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
         for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
           Expr *pE2 = pItem->pExpr;
           int iValToIns;