Fix issue when parsing large CPU Masks (+32C) systems

[benjojo]

Previously when using 32Thread+ systems, the libary would misparse the cores beyond the 32T threashold, causing bad behaviour.

This has now been fixed, with tests (and the parsing being moved to it's own testable sub-function)

Tested on a 12C*HT*2S, 32C*HT, and 32C*HT*2S system's output on modern linux kernels

[lrita]

Thanks for your reporting this issue. After I investigate the cpumap string format, it is outputed by this. We can find there only first phrase maybe less than 8 character. So I think the really correct parse function maybe:

func parseCPUMapMask(d string, cpucount int) Bitmask {
	cpumask := NewBitmask(cpucount)
	tokens := strings.Split(strings.TrimSpace(d), ",")
	base := 0
	for j := 0; j < len(tokens); j++ {
                token := tokens[len(tokens)-1-j]
                nn := len(token) * 4
		mask, _ := strconv.ParseUint(token, 16, 64)
		for k := 0; k < nn; k++ {
			if (mask>>uint64(k))&0x01 != 0 {
				cpumask.Set(k+base, true)
			}
		}
		base += nn
	}
	return cpumask
}

Can you improve your patch and verify it ?