Enable the clang-format pre-submit hook

Bug: 36699008
Test: Try to upload a patch with formatting errors.
Change-Id: I4af7d142ccbbaf39eb236547487c59c5ff8f2cd6

.clang-format

@@ -0,0 +1,28 @@
+#
+# Copyright (C) 2017 The Android Open Source Project
+#
+# 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.
+#
+
+#
+# Below are some minor deviations from the default Google style to
+# accommodate for handling of the large legacy code base.
+#
+
+BasedOnStyle: Google
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+AllowShortFunctionsOnASingleLine: Inline
+TabWidth: 4
+UseTab: Never
+IndentWidth: 4

PREUPLOAD.cfg

@@ -0,0 +1,5 @@
+[Options]
+ignore_merged_commits = true
+
+[Builtin Hooks]
+clang_format = true