Fix the problem it cannot use 'all' and 'total' simultaneously about CPU

I want to show the CPU utilization of all cores and the average of them at the same time.
However, I cannot use 'all' and 'total' simultaneously like this.
```bash
$ dstat -c -C all,total
-----cpu0-usage----------cpu1-usage----
usr sys idl wai stl:usr sys idl wai stl
  0   0 100   0   0:  0   0 100   0   0
```

I fix the problem it cannot use 'all' and 'total' simultaneously about CPU
```bash
$ dstat -c -C all,total
-----cpu0-usage----------cpu1-usage-------total-cpu-usage--
usr sys idl wai stl:usr sys idl wai stl:usr sys idl wai stl
  0   0 100   0   0:  0   0 100   0   0:  0   0 100   0   0
```