pragma_update fails with ExecuteReturnedResults

Ideally, while executing a batch, we should fail if it contains a SELECT
statement. But currently there is no way to make the distinction between
a SELECT and a PRAGMA which both updates and returns a row.
So we fail only when `extra_check` feature is activated.

src/lib.rs

@@ -451,7 +451,8 @@ impl Connection {
         let mut sql = sql;
         while !sql.is_empty() {
             let stmt = self.prepare(sql)?;
-            if !stmt.stmt.is_null() && stmt.step()? {
+            if !stmt.stmt.is_null() && stmt.step()? && cfg!(feature = "extra_check") {
+                // Some PRAGMA may return rows
                 return Err(Error::ExecuteReturnedResults);
             }
             let tail = stmt.stmt.tail();