Unsupported meant two things: a container this reader does not handle,
and metadata the image holds in a form the reader cannot decode, such as
a compressed .dep-v0 section. Both read as not_applicable, so an image
that carries metadata reported that the check did not apply.
Mark the second case on the format failure and carry it on
AnalysisUnsupportedTargetError, so the audit records a failed read and
stays unknown. The tools' own errors and messages do not change.
Matt Van Horn
a37b652388