aura: Explicitly disable GTK

build/linux/system.gyp

 # Copyright (c) 2011 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.
 
 {
   'conditions': [
     ['sysroot!=""', {
       'variables': {
         'pkg-config': './pkg-config-wrapper "<(sysroot)"',
       },
@@ skipping 450 matching lines @@
           '<!@(<(pkg-config) --libs-only-L --libs-only-other dbus-glib-1)',
         ],
         'libraries': [
           '<!@(<(pkg-config) --libs-only-l dbus-glib-1)',
         ],
       },
     },
     {
       'target_name': 'glib',
       'type': 'settings',
+      'toolsets': ['host', 'target'],
       'direct_dependent_settings': {
         'cflags': [
           '<!@(<(pkg-config) --cflags glib-2.0)',
         ],
       },
       'link_settings': {
         'ldflags': [
           '<!@(<(pkg-config) --libs-only-L --libs-only-other glib-2.0)',
         ],
         'libraries': [
@@ skipping 54 matching lines @@
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l wayland-client wayland-egl xkbcommon)',
             ],
           },
         }],
       ],
     },
   ],
 }