Improve thread reap handling

It's a bit of a mess currently, streamline and clean it up.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/time.c b/time.c
index 08ef078..11ee0e0 100644
--- a/time.c
+++ b/time.c
@@ -142,8 +142,6 @@
 {
 	int i;
 
-	fio_gettime(&genesis, NULL);
-
 	/*
 	 * Check the granularity of the nanosleep function
 	 */
@@ -164,6 +162,11 @@
 	}
 }
 
+void set_genesis_time(void)
+{
+	fio_gettime(&genesis, NULL);
+}
+
 void fill_start_time(struct timeval *t)
 {
 	memcpy(t, &genesis, sizeof(genesis));