Add BUILD.gn for tinyxml

#

#  Copyright (C) 2015 Google, Inc.

#

#  Licensed under the Apache License, Version 2.0 (the "License");

#  you may not use this file except in compliance with the License.

#  You may obtain a copy of the License at:

#

#  http://www.apache.org/licenses/LICENSE-2.0

#

#  Unless required by applicable law or agreed to in writing, software

#  distributed under the License is distributed on an "AS IS" BASIS,

#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

#  See the License for the specific language governing permissions and

#  limitations under the License.

#

static_library("tinyxml2") {

  sources = [

    "tinyxml2.cpp"

  ]

  include_dirs = [ "." ]

}