Emulate 64-bit atomic operations on 32-bit architectures by using a mutex.
Emulate 64-bit atomic operations on 32-bit architectures by using a mutex.

ok mpi@, jsg@

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