Make per device stats work for average after a stat zeroing.
diff --git a/cgminer.c b/cgminer.c
index a15818e..296531b 100644
--- a/cgminer.c
+++ b/cgminer.c
@@ -2324,7 +2324,7 @@ double cgpu_runtime(struct cgpu_info *cgpu)
struct timeval now;
double dev_runtime;
- if (cgpu->dev_start_tv.tv_sec == 0)
+ if (cgpu->dev_start_tv.tv_sec < total_tv_start.tv_sec)
dev_runtime = total_secs;
else {
cgtime(&now);