Build the openglui embedder conditionally

runtime/dart-runtime.gyp

 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 {
   'includes': [
     'tools/gyp/runtime-configurations.gypi',
     'vm/vm.gypi',
     'bin/bin.gypi',
     'third_party/double-conversion/src/double-conversion.gypi',
     'third_party/jscre/jscre.gypi',
     '../tools/gyp/source_filter.gypi',
   ],
   'variables': {
     'version_in_cc_file': 'vm/version_in.cc',
     'version_cc_file': '<(SHARED_INTERMEDIATE_DIR)/version.cc',
+
+    # Disable the OpenGLUI embedder by default on desktop OSes.  Note,
+    # to build this on the desktop, you need GLUT installed.
+    'enable_openglui%': 0,
   },
+  'conditions': [
+    ['OS=="android" or enable_openglui==1', {
+        'includes': [
+          'embedders/openglui/openglui_embedder.gypi',
+        ],
+      },
+    ],
+  ],
   'targets': [
     {
       'target_name': 'libdart',
       'type': 'static_library',
       'dependencies': [
         'libdart_lib',
         'libdart_vm',
         'libjscre',
         'libdouble_conversion',
         'generate_version_cc_file',
@@ skipping 70 matching lines @@
     },
     {
       'target_name': 'runtime_packages',
       'type': 'none',
       'dependencies': [
         '../pkg/pkg.gyp:pkg_packages',
       ],
     },
   ],
 }