Remove GYP files.

third_party/jsoncpp/jsoncpp_nacl.gyp

-# Copyright 2014 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_untrusted.gypi',
-    'jsoncpp.gypi',
-  ],
-  'conditions': [
-    ['disable_nacl==0 and disable_nacl_untrusted==0', {
-      'targets': [
-        {
-          'target_name': 'jsoncpp_nacl',
-          'type': 'none',
-          'variables': {
-            'nacl_untrusted_build': 1,
-            'nlib_target': 'libjsoncpp_nacl.a',
-            'build_newlib': 1,
-          },
-          'compile_flags': [
-            # Turn off optimizations based on strict aliasing
-            # because of the workaround at
-            # overrides/src/lib_json/json_value.cpp:38.
-            '-fno-strict-aliasing',
-          ],
-        },
-      ],
-    }],
-  ],
-}