message: add copyright header to fb303-config.cmake.in
  Summary: fb303-config.cmake.in was missing a copyright header. Add one.
diff: +# Copyright 2019-present Facebook, 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.
  +
  @PACKAGE_INIT@
  set_and_check(FB303_INCLUDE_DIR "@PACKAGE_INCLUDE_INSTALL_DIR@")
  