支持 windows平台 Linux平台和 Apple平台

#if defined WIN32 || defined _WIN32
#include <windows.h>
#endif
//获取CPU数量
static int XGetCpuNum()
{
#if defined WIN32 || defined _WIN32
    SYSTEM_INFO sysinfo;
    GetSystemInfo(&sysinfo);

    return (int)sysinfo.dwNumberOfProcessors;
#elif defined __linux__
    return (int)sysconf(_SC_NPROCESSORS_ONLN);
#elif defined __APPLE__
    int numCPU = 0;
    int mib[4];
    size_t len = sizeof(numCPU);

    // set the mib for hw.ncpu
    mib[0] = CTL_HW;
    mib[1] = HW_AVAILCPU;  // alternatively, try HW_NCPU;

                           // get the number of CPUs from the system
    sysctl(mib, 2, &numCPU, &len, NULL, 0);

    if (numCPU < 1)
    {
        mib[1] = HW_NCPU;
        sysctl(mib, 2, &numCPU, &len, NULL, 0);

        if (numCPU < 1)
            numCPU = 1;
    }
    return (int)numCPU;
#else
    return 1;
#endif
}