cmake: Add copyright header

Summary: The Open Source Team's Automated Checkup tool requires it and who are we mere mortals to argue with our bots overloads?

Reviewed By: lmvasquezg

Differential Revision: D88754025

fbshipit-source-id: b4e7758c595cc7ecce54bb75e4f8e1788efb5d39

Author: Pierre Chevalier

build/fbcode_builder/CMake/Findibverbs.cmake

@@ -1,3 +1,17 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# 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.
+
 # Find the ibverbs libraries
 #
 # The following variables are optionally searched for defaults