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

build/linux/unbundle/libwebp.gyp

Index: build/linux/unbundle/libwebp.gyp
diff --git a/build/linux/unbundle/libwebp.gyp b/build/linux/unbundle/libwebp.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..6dbce2e3ab876cf003a5e8a01b7d595731b2517a
--- /dev/null
+++ b/build/linux/unbundle/libwebp.gyp
@@ -0,0 +1,28 @@
+# Copyright 2013 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': 'libwebp',
+      'type': 'none',
+      'direct_dependent_settings': {
+        'defines': [
+          'ENABLE_WEBP',
+        ],
+      },
+      'link_settings': {
+        'libraries': [
+          # Check for presence of webpdemux library, use it if present.
+          '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+          '--code "int main() { return 0; }" '
+          '--run-linker '
+          '--on-success "-lwebp -lwebpdemux" '
+          '--on-failure "-lwebp" '
+          '-- -lwebpdemux)',
+        ],
+      },
+    }
+  ],
+}