Add more checks to the cpu collector

[erichte-ibm]

The CPU collector should at least the following stats:

Alpha:

• frequency (ppc64) - use ppc64_cpu --frequency
• number of threads - lscpu
• cpu model - lscpu or cat /proc/cpuinfo
• cpu version/revision - same

1.0+ release:

• SMT on/off - use either lscpu or ppc64_cpu --smt (optional? inferrable from num threads)
• frequency (x86)
• powersave/governor/etc
• amount of cache (may belong in the memory section?)
• physical vs virtual (perhaps in a new vm.rs collector group?)

[erichte-ibm]

consider nproc versus /proc/cpuinfo, for getting number of CPUs actually available to the process

https://www.flamingspork.com/blog/2020/11/25/why-you-should-use-nproc-and-not-grep-proc-cpuinfo/