[SE] Add .clang-format
The .clang-tidy file is copied from the top-level LLVM source directory.
Also fix warnings generated by clang-format:
* Moved SimpleHostPlatformDevice.h so its header include guard could
have the right format.
* Changed signatures of methods taking llvm::Twine by value to take it
by const ref instead.
* Add "noexcept" to some move constructors and assignment operators.
* Removed a bunch of places where single-statement loops and
conditionals were surrounded with braces. (This was not found by the
current clang-tidy, but with a local patch that I hope to upstream
Reviewers: jlebar, jprice
Differential Revision: https://reviews.llvm.org/D24468
19 files changed