Add ECANCELED and EOVERFLOW. For canceled (async) operations and conversion overflows, respectively. (EOVERFLOW from espie@)
Add ECANCELED and EOVERFLOW. For canceled (async) operations and conversion
overflows, respectively. (EOVERFLOW from espie@)

don't bump libc, as there are currently no functions that use them, but it
doesn't hurt to have them around.

as discussed with deraadt@, espie@, miod@ and otto@
ok deraadt@ espie@ miod@ otto@

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