macOS requires the debug symbols to either be part of the intermediate
object file `whatever.o` or a companion `whatever.dSym` bundle. The
former case seems ill-suited for our needs since it subscribes to
the old-fashioned compilation strategy using intermediate compilation
units; the latter is what we need however on macOS the debug symbols
unlike in Elf are not part of the final artefact; rather they sit
next to it in its own Mach-O file.
