Fix sqlite sample import.

Change-Id: I71bde1d7f15912a628e15572b51350bb768c78c6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/97935
Reviewed-by: Samir Jindel <sjindel@google.com>

samples/ffi/sqlite/test/sqlite_test.dart

@@ -2,7 +2,7 @@
 
 import "package:test/test.dart";
 
-import 'package:sqlite3/sqlite.dart';
+import '../lib/sqlite.dart';
 
 void main() {
   test("sqlite integration test", () {