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

build/config/allocator.gni

Index: build/config/allocator.gni
diff --git a/build/config/allocator.gni b/build/config/allocator.gni
new file mode 100644
index 0000000000000000000000000000000000000000..71418a8e772d991249b66f5f75c606f446be4a6c
--- /dev/null
+++ b/build/config/allocator.gni
@@ -0,0 +1,16 @@
+# 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.
+
+# TODO(GYP): Make tcmalloc work on win.
+if (is_android || current_cpu == "mipsel" || is_mac || is_ios || is_asan ||
+    is_lsan || is_tsan || is_msan || is_win) {
+  _default_allocator = "none"
+} else {
+  _default_allocator = "tcmalloc"
+}
+
+declare_args() {
+  # Memory allocator to use. Set to "none" to use default allocator.
+  use_allocator = _default_allocator
+}