{macOS} Symbol lookup fails when "Generate separate debug info" checked

When "Generate separate debug info" is checked in Qt Creator, the `atos` lookup fails.

For starters, the .pri file needs `QMAKE_CFLAGS_RELEASE_WITH_DEBUGINFO` and `QMAKE_CPPFLAGS_RELEASE_WITH_DEBUGINFO` options modified like the others to turn off optimization.

Then the `atos` command needs to be changed to handle the external dSYM file (I think?).

I don't plan to do this, but if someone wants to take a swing at it, please feel free.

Start by inspecting the .pri file's release-with-debuginfo flags and the existing atos command. Verify how the external dSYM is produced and passed to atos; done means symbol lookup succeeds when Qt Creator's "Generate separate debug info" option is enabled.

Written by the indexing model from the issue text.