Update clang-format settings. To allow for extern "C" declarations to not break on a brace. This preserves the current code style. Also add indented preprocessor definitions. This makes the formatting of "platform.h" much nicer. Bug: angleproject:2971 Change-Id: I392babe0c8d67539a8e026a36a023a7404bb63c2 Reviewed-on: https://chromium-review.googlesource.com/c/1347452 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>