Remove GYP files.

third_party/jsoncpp/jsoncpp.gypi

-# Copyright 2013 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.
-
-{
-  'target_defaults': {
-    'defines': [
-      'JSON_USE_EXCEPTION=0',
-    ],
-    'sources': [
-      'source/include/json/assertions.h',
-      'source/include/json/autolink.h',
-      'source/include/json/config.h',
-      'source/include/json/features.h',
-      'source/include/json/forwards.h',
-      'source/include/json/json.h',
-      'source/include/json/reader.h',
-      'overrides/include/json/value.h',
-      'source/include/json/writer.h',
-      'source/src/lib_json/json_batchallocator.h',
-      'overrides/src/lib_json/json_reader.cpp',
-      'source/src/lib_json/json_tool.h',
-      'overrides/src/lib_json/json_value.cpp',
-      'source/src/lib_json/json_writer.cpp',
-    ],
-    'include_dirs': [
-      '../..',
-      'overrides/include/',
-      'source/include/',
-      'source/src/lib_json/',
-    ],
-    'direct_dependent_settings': {
-      'include_dirs': [
-        'overrides/include/',
-        'source/include/',
-      ],
-    },
-  },
-}