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
Fixed the colours so that they work with all of the default Terminal
presets. Also changed things so that when colour is off, we only use
ASCII characters in our source code displays.
rdar://105452194
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
