MacOS (and all apple targets) have -Csplit-debuginfo=packed as default
instead of "off" like all other targets (well there is Windows, but we
don't test it in those tests), also -Csplit-debuginfo is not stable on
all targets so we only set in on Darwin where is matters.
apparently I missed some tests in the last commit. Rather than having
dozens of tests use the long version, use the short version in
`run-make` and the long version in `run-make-fulldeps` (which is now
only three tests)
