[PATCH] D24222: Add missing _US_ACTION_MASK constant to unwind.h

[Dimitry Andric via llvm-commits]

dim added a comment.

One additional note: it seems libgcc and other unwinders use `_US_ACTION_MASK` to mask out the `_US_UNWIND_FRAME_STARTING` and `_US_UNWIND_FRAME_RESUME` values, as they handle `_US_FORCE_UNWIND` (and `_US_END_OF_STACK` which we also don't have) separately.  It doesn't look like libunwind uses this method?


https://reviews.llvm.org/D24222