[clang-tidy] Fix clang-tidy errors from g3/gsys config

Fix the clang-tidy errors found here: https://paste.googleplex.com/6044161211105280
Also add dummy .clang-tidy to prevent errors being thrown from xyz/
directory and auto-generated .pb.h files

Google-Bug-Id: 380138738
Change-Id: Iebc449b4d633c603739a4d752a24d77527ebd346
Signed-off-by: David Tang <davtang@google.com>
9 files changed