[PATCH] Time and seek optimizations

We did too many gettimeofday() calls, this patch cuts the number by
40%. Use clock_gettime() MONOTONIC instead, it is faster on my system
at least.

This patch also optimizes calling lseek() only when necessary for the
sync io engine.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/eta.c b/eta.c
index 339f656..99e59ec 100644
--- a/eta.c
+++ b/eta.c
@@ -238,7 +238,7 @@
 	if (mtime > 1000) {
 		r_rate = (io_bytes[0] - prev_io_bytes[0]) / mtime;
 		w_rate = (io_bytes[1] - prev_io_bytes[1]) / mtime;
-		gettimeofday(&prev_time, NULL);
+		fio_gettime(&prev_time, NULL);
 		memcpy(prev_io_bytes, io_bytes, sizeof(io_bytes));
 	}