NetBSD commit log:

Use a constant array for the MIB. Newer LLVM decided that mib[] warranted
stack protections, with the obvious crash after the setup was done.
As a positive side effect, code size shrinks a bit.

I'm not sure why this hasn't bitten us yes, but it is certainly possible and
there are no real drawbacks to this change anyway.

Submitted by: pfg
Obtained from: NetBSD
MFC after: 1 week