These weren't working correctly because I made the unwinder call
`_swift_task_getCurrent()`, but of course when out-of-process, it calls
that in `swift-backtrace`, which is wrong. Remove that for now.
While I'm here, I also tweaked the formatting slightly, and I noticed
that we were saying that all thunks were also system functions, which
seemed unnecessary and odd.
Plus there were a couple of extra system functions I added to make the
async crash backtraces nicer in friendly mode.
rdar://106363539
Some symbolication frameworks have a symbol cache; we probably don't want
to use that for test cases, to avoid running into problems where the cache
holds stale information.
rdar://105409147
Just use `UInt` for `Address`. This is still the subject of some discussion
on the forums, but I haven't decided precisely what to do about it and `UInt`
makes sense for now. This also necessitated some casts elsewhere.
Improve some comments.
Made `limit` robust against silly negative values.
A couple of formatting fixes.
Don't bother supporting the macOS 10.12.2 SDK as Xcode now supports a minimum
of 10.13.
Removed some unnecessary memory rebinding.
Made `CFString` conversion slightly more efficient.
Provide the `SharedCacheInfo` fields everywhere, but make it optional all
over as well.
rdar://104336548
Adds a new swift_Backtracing library, with a corresponding _Backtracing
module, to the build. Also add some tests.
This is not public API at this point, but will be used by the external
backtracing program, `swift-backtrace`.
rdar://104336548
