Use nullptr explicitly

Author: alinaliBQ

cpp/src/arrow/flight/sql/odbc/tests/statement_test.cc

@@ -1238,7 +1238,7 @@ TEST_F(StatementRemoteTest, DISABLED_TestSQLExtendedFetchQueryNullIndicator) {
   // server instead. Mock server has type `DENSE_UNION` for null column data.
   SQLINTEGER val;
 
-  ASSERT_EQ(SQL_SUCCESS, SQLBindCol(this->stmt, 1, SQL_C_LONG, &val, 0, 0));
+  ASSERT_EQ(SQL_SUCCESS, SQLBindCol(this->stmt, 1, SQL_C_LONG, &val, 0, nullptr));
 
   std::wstring wsql = L"SELECT null as null_col;";
   std::vector<SQLWCHAR> sql0(wsql.begin(), wsql.end());