[ffigen] Prevent warnings in FfiNative example (#479)

pkgs/ffigen/example/ffinative/generated_bindings.dart

diff --git a/pkgs/ffigen/example/ffinative/generated_bindings.dart b/pkgs/ffigen/example/ffinative/generated_bindings.dart
index ea0436b..1bb65d0 100644
--- a/pkgs/ffigen/example/ffinative/generated_bindings.dart
+++ b/pkgs/ffigen/example/ffinative/generated_bindings.dart
@@ -1,3 +1,5 @@
+// ignore_for_file: deprecated_member_use
+
 // AUTO GENERATED FILE, DO NOT EDIT.
 //
 // Generated by `package:ffigen`.

pkgs/ffigen/example/ffinative/pubspec.yaml

diff --git a/pkgs/ffigen/example/ffinative/pubspec.yaml b/pkgs/ffigen/example/ffinative/pubspec.yaml
index 5ba0423..2132d8b 100644
--- a/pkgs/ffigen/example/ffinative/pubspec.yaml
+++ b/pkgs/ffigen/example/ffinative/pubspec.yaml
@@ -23,3 +23,5 @@
   headers:
     entry-points:
       - 'headers/example.h'
+  preamble: |
+    // ignore_for_file: deprecated_member_use

pkgs/ffigen/test/example_tests/ffinative_example_test.dart

diff --git a/pkgs/ffigen/test/example_tests/ffinative_example_test.dart b/pkgs/ffigen/test/example_tests/ffinative_example_test.dart
index 6895a8e..779b41a 100644
--- a/pkgs/ffigen/test/example_tests/ffinative_example_test.dart
+++ b/pkgs/ffigen/test/example_tests/ffinative_example_test.dart
@@ -26,6 +26,8 @@
 ${strings.headers}:
   ${strings.entryPoints}:
     - 'example/ffinative/headers/example.h'
+${strings.preamble}: |
+  // ignore_for_file: deprecated_member_use
 ''') as YamlMap);
       final library = parse(config);