upstreamed in Hamlib/Hamlib#1024
--- a/rigs/prm80/prm80.h
+++ b/rigs/prm80/prm80.h
@@ -23,6 +23,7 @@
#define _PRM80_H 1
#include <hamlib/rig.h>
+#include <sys/time.h>
#include "misc.h"
#define BACKEND_VER "20210416"