third_party: Add wayland library.

build/linux/system.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.
 
 {
   'variables': {
     # If any of the linux_link_FOO below are set to 1, then the corresponding
     # target will be linked against the FOO library (either dynamically or
     # statically, depending on the pkg-config files), as opposed to loading the
     # FOO library dynamically with dlopen.
@@ skipping 1250 matching lines @@
                       '-Wno-header-guard',
                     ],
                   },
                 }],
               ],
             }],
           ]
         }],
       ],
     },
+    {
+      'target_name': 'libffi',
+      'type': 'none',
+      'conditions': [
+        ['_toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags libffi)',
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(<(pkg-config) --libs-only-L --libs-only-other libffi)',
+            ],
+            'libraries': [
+              '<!@(<(pkg-config) --libs-only-l libffi)',
+            ],
+          },
+        }],
+      ],
+    },
   ],
 }