Make checkdeps.py check third_party.

third_party/libevent/libevent.gyp

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     {
       'target_name': 'libevent',
       'product_name': 'event',
       'type': 'static_library',
       'toolsets': ['host', 'target'],
       'sources': [
         'buffer.c',
         'evbuffer.c',
         'evdns.c',
         'event.c',
         'event_tagging.c',
         'evrpc.c',
         'evutil.c',
         'http.c',
         'log.c',
         'poll.c',
         'select.c',
         'signal.c',
         'strlcpy.c',
       ],
       'defines': [
         'HAVE_CONFIG_H',
       ],
+      'include_dirs': [
+        '../..',
+      ],
       'conditions': [
         # libevent has platform-specific implementation files.  Since its
         # native build uses autoconf, platform-specific config.h files are
         # provided and live in platform-specific directories.
         [ 'OS == "linux" or (OS == "android" and _toolset == "host")', {
           'sources': [ 'epoll.c' ],
           'include_dirs': [ 'linux' ],
           'link_settings': {
             'libraries': [
               # We need rt for clock_gettime().
@@ skipping 12 matching lines @@
           'include_dirs': [ 'mac' ]
         }],
         [ 'OS == "solaris"', {
           'sources': [ 'devpoll.c', 'evport.c' ],
           'include_dirs': [ 'solaris' ]
         }],
       ],
     },
   ],
 }