Hold interrupts blocked while comparing a cached node's refcount to zero and freeing the node. Just in case an interrupt happens to ref the node after the refcount was checked but before the node is freed. Tested by several as part of a larger diff.
Hold interrupts blocked while comparing a cached node's refcount to zero
and freeing the node. Just in case an interrupt happens to ref the node after
the refcount was checked but before the node is freed.
Tested by several as part of a larger diff.

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