Fix some cpu_switchto fallout. Reading disklabels to find raid components was causing some systems to hang. The hangs were due to tsleep() being called before it was prudent to do so.
Fix some cpu_switchto fallout. Reading disklabels to find raid
components was causing some systems to hang. The hangs were due to
tsleep() being called before it was prudent to do so.

Create a startup hook to find the raid components when it is safe to
encounter tsleep() but before root is mounted.

Noticed and fix tested by Josh Grosse (who proved the cpu_switchto
link), merdely@, fkr@.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars