t_ringbuf.c: Suspicious useless variable j in upause() function

[liuqun]

portable-lib/test/t_ringbuf.c

Lines 188 to 199 in 9b47975

	// Simple busywait.
	// usleep() is not granular enough
	static void
	upause(int n)
	{
	int i;
	volatile uint64_t j = sys_cpu_timestamp();
	for (i = 0; i < n; ++i) {
	j += i;
	rte_pause();
	}
	}

Maybe simply asm("nop") is better:

     for (i = 0; i < n; ++i) { 
         asm("nop");
         rte_pause(); 
     }