Fix #3236 (#3633)

Fix #3236 (#3633)

* networkd: condition_test() can return a negative error, handle that

If a condition check fails with an error we should not consider the check
successful. Fix that.

We should probably also improve logging in this case, but for now, let's just
unbreak this breakage.

Fixes: #3236

* condition: handle unrecognized architectures nicer

When we encounter a check for an architecture we don't know we should not
let the condition check fail with an error code, but instead simply return
false. After all the architecture might just be newer than the ones we know, in
which case it's certainly not our local one.

Fixes: #3236