NetBSD port

[0-wiz-0]

I've started a NetBSD port based mostly on the FreeBSD one. My work is here.

It currently fails to build:

   Compiling sysctl v0.6.0 (sysctl-rs-fork)
error[E0425]: cannot find function `sysctlnametomib` in crate `libc`
  --> src/unix/funcs.rs:26:15
   |
26 |         libc::sysctlnametomib(
   |               ^^^^^^^^^^^^^^^ not found in `libc`

error[E0599]: no method named `is_temperature` found for struct `ctl_info::CtlInfo` in the current scope
   --> src/unix/funcs.rs:199:13
    |
199 |     if info.is_temperature() {
    |             ^^^^^^^^^^^^^^ method not found in `CtlInfo`
    |
   ::: src/ctl_info.rs:8:1
    |
8   | pub struct CtlInfo {
    | ------------------ method `is_temperature` not found for this struct

error[E0425]: cannot find function `temperature` in this scope
   --> src/unix/funcs.rs:200:16
    |
200 |         return temperature(&info, &val);
    |                ^^^^^^^^^^^ not found in this scope

The first is a problem in the libc crate which @0323pin is working on fixing. I'm a bit confused by the other too - how do these work on other non-FreeBSD systems? I don't see is_temperature() defined except for FreeBSD, but I must have overlooked something.