Swift 5.9 includes built in crash reporting, printing stack traces,
libraries, and registers to stdout/err.
https://www.swift.org/blog/swift-5.9-backtraces/
As (Core)Foundation is written in Swift nowadays, we get this feature
for free even in our "C++" apps, as we always link to CoreFoundation.
Our test binaries have been taught how to hook into this, so the
remaining step is to enable it via the SWIFT_BACKTRACE env var.
Pick-to: 6.9
Change-Id: I72dbd9ea934ecc3091766456509f4bd42b2bdab8
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
