Free stratum buffers added to the work struct when freeing work ram.

cgminer.c

@@ -2190,6 +2190,11 @@ static struct work *make_work(void)
 
 static void free_work(struct work *work)
 {
+	if (work->stratum) {
+		free(work->job_id);
+		free(work->nonce2);
+		free(work->ntime);
+	}
 	free(work);
 }