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

build/android/pack_relocations.gypi

+# Copyright 2014 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.
+
+# This file is meant to be included into an action to provide a rule that
+# packs relocations in Release builds of native libraries.
+#
+# To use this, create a gyp target with the following form:
+#  {
+#    'action_name': 'pack_relocations',
+#    'actions': [
+#      'variables': {
+#        'enable_packing': 'pack relocations if 1, plain file copy if 0'
+#        'exclude_packing_list': 'names of libraries explicitly not packed',
+#        'ordered_libraries_file': 'file generated by write_ordered_libraries'
+#        'input_paths': 'files to be added to the list of inputs'
+#        'stamp': 'file to touch when the action is complete'
+#        'stripped_libraries_dir': 'directory holding stripped libraries',
+#        'packed_libraries_dir': 'directory holding packed libraries',
+#      'includes': [ '../../build/android/pack_relocations.gypi' ],
+#    ],
+#  },
+#
+
+{
+  'variables': {
+    'input_paths': [],
+  },
+  'inputs': [
+    '<(DEPTH)/build/android/gyp/util/build_utils.py',
+    '<(DEPTH)/build/android/gyp/pack_relocations.py',
+    '<(ordered_libraries_file)',
+    '>@(input_paths)',
+  ],
+  'outputs': [
+    '<(stamp)',
+  ],
+  'conditions': [
+    ['enable_packing == 1', {
+      'message': 'Packing relocations for <(_target_name)',
+      'dependencies': [
+        '<(DEPTH)/third_party/android_platform/relocation_packer.gyp:android_relocation_packer#host',
+      ],
+      'inputs': [
+        '<(PRODUCT_DIR)/android_relocation_packer',
+      ],
+      'action': [
+        'python', '<(DEPTH)/build/android/gyp/pack_relocations.py',
+        '--configuration-name=<(CONFIGURATION_NAME)',
+        '--enable-packing=1',
+        '--exclude-packing-list=<@(exclude_packing_list)',
+        '--android-pack-relocations=<(PRODUCT_DIR)/android_relocation_packer',
+        '--stripped-libraries-dir=<(stripped_libraries_dir)',
+        '--packed-libraries-dir=<(packed_libraries_dir)',
+        '--libraries=@FileArg(<(ordered_libraries_file):libraries)',
+        '--stamp=<(stamp)',
+      ],
+    }, {
+      'message': 'Copying libraries (no relocation packing) for <(_target_name)',
+      'action': [
+        'python', '<(DEPTH)/build/android/gyp/pack_relocations.py',
+        '--configuration-name=<(CONFIGURATION_NAME)',
+        '--enable-packing=0',
+        '--stripped-libraries-dir=<(stripped_libraries_dir)',
+        '--packed-libraries-dir=<(packed_libraries_dir)',
+        '--libraries=@FileArg(<(ordered_libraries_file):libraries)',
+        '--stamp=<(stamp)',
+      ],
+    }],
+    ['component == "shared_library"', {
+      # Add a fake output to force the build to always re-run this step. This
+      # is required because the real inputs are not known at gyp-time and
+      # changing base.so may not trigger changes to dependent libraries.
+      'outputs': [ '<(stamp).fake' ]
+    }],
+  ],
+}