[darwin] CPUInfo: remove duplicated CPU features reading and update ReadCPUFeatures(), fix potential buffer overrun
[win32] CPUInfo: properly initialize CPU cores info under win32
CPUInfo::getUsedPercentage: round result
[win32] CPUInfo: implement reading current frequency and CPU cores loads
CPUInfo::GetCoresUsageString: refactoring, simplify output string
CPUInfo: cleanup
CPUInfo: ctor: trim first and last tab if any