Add a basic .clang-tidy file and fix typedef warnings

This initial .clang-tidy file only enforces the use of 'using' instead
of 'typedef'.

Note that a second .clang-tidy is added to the filter sub-folder to
disable checks against generated code.

The entire tree can be checked by running `run-clang-tidy` after
generating a compilation command database. I personally use `bear`
to generate `compile_commands.json`.

$ ./configure
$ bear -- make -j$(nproc)
$ run-clang-tidy -fix

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I074b6f2724e1af9a2df311e07a2fcdacb689bcf5