sysctl hw.model does not exist on arm[64]?

[Hyun Hwang]

Hi,

I'm currently running the armv7 build of r329609 on my Raspberry Pi 2. I just installed sysutils/bsdstats, and upon the first time sending the report, this happened:
```
Posting OS statistics to rpt.bsdstats.org ... SUCCESS
Posting device statistics to rpt.bsdstats.org ... SUCCESS
sysctl: unknown oid 'hw.model'
Posting CPU information to rpt.bsdstats.org ... SUCCESS
Posting port statistics to rpt.bsdstats.org ... SUCCESS
```
The same thing is expected to happen on aarch64 build (RPi3) because it does not exist on that arch, too.

Is this an expected/intended behavior? Because on my amd64 machine, `sysctl hw.model` shows the CPU info: `Intel(R) Core(TM) i3-5005U CPU @ 2.00GHz`
-- 
Hyun Hwang