This PR adds support for reading the frequency of Apple Silicon
M1/M2 CPUs. We do so by reading the values out of the IOKit
framework, as a few other projects have now demonstrated to be
possible. This requires the use of CGO. The library provides a
convenience IsAppleSilicon() guard to detect whether the values
can be read.
Currently gopsutil does not support the big.LITTLE CPU architectures
(i think?) - in fact the P and E cores have different max frequencies.
For now, just read the P core frequency. The E core data is readily
available if we want to read it in the future.
Closes#1000
Small example program
```go
package main
import (
"fmt"
"github.com/shoenig/go-m1cpu"
"github.com/shirou/gopsutil/v3/cpu"
)
func main() {
fmt.Println("is Apple Silicon:", m1cpu.IsAppleSilicon())
fmt.Println("model name", m1cpu.ModelName())
fmt.Println("pCore GHz", m1cpu.PCoreGHz())
fmt.Println("eCore GHz", m1cpu.ECoreGHz())
fmt.Println("pCore Hz", m1cpu.PCoreHz())
fmt.Println("eCore Hz", m1cpu.ECoreHz())
fmt.Println("----- gopsutil ----")
infos, err := cpu.Info()
if err != nil {
panic(err)
}
for _, info := range infos {
fmt.Println("info.Mhz", info.Mhz)
}
}
```
```shell
go run main.go
is Apple Silicon: true
model name Apple M2 Pro
pCore GHz 3.504
eCore GHz 2.424
pCore Hz 3504000000
eCore Hz 2424000000
----- gopsutil ----
info.Mhz 3.504e+09
```
