Conform to LLVM coding style

[dylanmckay]

We need to conform to LLVM's coding style. In the future, we would like to be integrated into LLVM's trunk, and so this is mandatory.

We can use clang-format to do this. Note that this will touch a large amount of the codebase, so it is better to do this earlier.

We should also add a clang-check verification step into travis-ci, so that our codebase stays conformant.

[dylanmckay]

I have previously clang-format'd the source before the upstreaming process began.