Allow additional build failures and workaround for arm64

By default, rustc-mozilla allows 12 failures for armhf, however, in Apertis infrastructure additional failures are seen, so increase the number of failures allowed.

Also, currently due to an issue when building for arm64 on Debian a workaround is provided to disable outline-atomics, however the check used to activate the workaround is performed against distribution, and fails on Apertis.

Since this branch is specific for v2021, force to apply the workaround.

Signed-off-by: Walter Lozano walter.lozano@collabora.com