We need a minimum target of 15.7 or below because of CI, so add a new
`BacktracingDT 6.2` define. This is a bit of a hack for now to
unblock CI upgrades; we can go and clean things up and perhaps
generalise this mechanism later.
rdar://172129091
Also fix things so that we use the right path separator, depending
on image type, and add support for `DW_AT_specification` attributes
on `DW_TAG_subprogram` entries.
rdar://101623384
DWARF 3 doesn't have the `maximum_operations_per_instruction` field
in the line number header. As a result, we were mis-reading the
subsequent fields in the DWARF line table header.
rdar://168996222
This is slightly complicated by us currently not supporting this code
on iOS/tvOS/watchOS/visionOS. We should fix that, at which point we
can use the `SwiftStdlib`/`StdlibDeploymentTarget` macros instead.
rdar://164850733
Move the backtracing code into a new Runtime module. This means renaming
the Swift Runtime's CMake target because otherwise there will be a name
clash.
rdar://124913332
Alastair Houghton
Jesse Zamora
Johannes Weiss