Linux: add support for SELinux.

sandbox/sandbox.gyp

 # Copyright (c) 2009 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.
 
 {
   'includes': [
     '../build/common.gypi',
   ],
   'conditions': [
-    [ 'OS=="linux"', {
+    [ 'OS=="linux" and selinux==0', {
       'targets': [
         {
           'target_name': 'chrome_sandbox',
           'type': 'executable',
           'sources': [
             'linux/suid/sandbox.c',
           ],
           'include_dirs': [
             '..',
           ],
@@ skipping 41 matching lines @@
                 'linux/seccomp/trusted_process.cc',
                 'linux/seccomp/trusted_thread.cc',
                 'linux/seccomp/x86_decode.cc',
                 'linux/seccomp/x86_decode.h',
               ],
             },
           ],
         ]},
       ],
     }],
+    [ 'OS=="linux" and selinux==1', {
+      # GYP requires that each file have at least one target defined.
+      'targets': [
+        {
+          'target_name': 'sandbox',
+          'type': 'settings',
+        },
+      ],
+    }],
     [ 'OS=="win"', {
       'targets': [
         {
           'target_name': 'sandbox',
           'type': '<(library)',
           'dependencies': [
             '../testing/gtest.gyp:gtest',
             '../base/base.gyp:base',
           ],
           'msvs_guid': '881F6A97-D539-4C48-B401-DF04385B2343',
@@ skipping 241 matching lines @@
             'POCDLL_EXPORTS',
           ],
           'include_dirs': [
             '..',
           ],
         },
       ],
     }],
   ],
 }