Clear out saved time stamps after setting the clock.

When we create a discontinuity in the clock time, we must avoid mixing
local time stamps from before and after the jump.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

clock.c

@@ -416,6 +416,8 @@ enum servo_state clock_synchronize(struct clock *c,
 		break;
 	case SERVO_JUMP:
 		clock_step(c->clkid, -c->master_offset);
+		c->t1 = tmv_zero();
+		c->t2 = tmv_zero();
 		break;
 	case SERVO_LOCKED:
 		clock_ppb(c->clkid, -adj);