message: Fix slower CV_PAUSE on SkyLake and above.
  This is fixing
diff: @@ -52,11 +52,14 @@ DECLARE_CV_PAUSE
  #endif
  #ifndef CV_PAUSE
  # if defined __GNUC__ && (defined __i386__ || defined __x86_64__)
  +# include <x86intrin.h> /* for __rdtsc */
  # if !defined(__SSE2__)
  static inline void cv_non_sse_mm_pause() { __asm__ __volatile__ ("rep; nop"); }
  # define _mm_pause cv_non_sse_mm_pause
  # endif
  -# define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { _mm_pause(); } } while (0)
  +// 5 * v is meants for backward compatibility: with pre-Skylake CPUs, _mm_pause took 4 or 5 cycles.
  +// With post-Skylake CPUs, _mm_pause takes 140 cycles.
  +# define CV_PAUSE(v) do { const uint64_t __delay = 5 * v; uint64_t __init = __rdtsc(); do { _mm_pause(); } while ((__rdtsc() - __init) < __delay); } while (0)
  # elif defined __GNUC__ && defined __aarch64__
  # define CV_PAUSE(v) do { for (int __delay = (v); __delay > 0; --__delay) { asm volatile("yield" ::: "memory"); } } while (0)
  # elif defined __GNUC__ && defined __arm__
  