Detect failures for mandatory arches only using .fail files

Previously, we just used the failures directory to check if any
failure had happened for the submit prefix.
But this does not work properly when non-mandatory architectures are
used, their failure should not be fatal.

Instead, use .fail files and mark as a failure only if failed for
one of the mandatory architectures.

0 files changed, 0 insertions, 0 deletions