There's still vestiges of the libunwind experiment; I'm leaving those in even
though they're dead since I think we should move soon back to that approach.

Changed the indentation of pretty much the entire codebase.

It did some things that I don't like that seem not configurable,
but overall it seems like an improvement, and nice to have a
canonical format going forward.

Add an extra marker to libunwind so that pyston can ensure it's running on a patched libunwind version

Also, set -Wno-extern-c-compat to silence libunwind-related warnings.
Fixes #27, hopefully for real this time.

This doesn't surface if you install libunwind globally since clang will
ignore errors from system libraries; this change should fix it for people
who are installing libunwind locally (as is the goal).
Fixes #27