Add a snapshot of flutter/engine/src/build to our sdk

build/android/ndk.gyp

Index: build/android/ndk.gyp
diff --git a/build/android/ndk.gyp b/build/android/ndk.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..2838a9857e991184cf3a7adf039b8d380dd6fb4b
--- /dev/null
+++ b/build/android/ndk.gyp
@@ -0,0 +1,20 @@
+# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'targets': [
+    {
+      'target_name': 'cpu_features',
+      'type': 'static_library',
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '<(android_ndk_root)/sources/android/cpufeatures',
+        ],
+      },
+      'sources': [
+        '<(android_ndk_root)/sources/android/cpufeatures/cpu-features.c',
+      ],
+    },
+  ],
+}