If M_CANFAIL is set and the malloc() size is to big return NULL instead of panic()'ing.
If M_CANFAIL is set and the malloc() size is to big
return NULL instead of panic()'ing.

ok pedro@, deraadt@

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