silence clan warning

Index: macaddr.h
--- macaddr.h.orig
+++ macaddr.h
@@ -185,7 +185,7 @@ struct mac_addr {
 	}
 
     inline mac_addr(int in) {
-		in = in; // Silence gcc
+	static_cast<void>(in);
         longmac = 0;
         longmask = 0;
         error = 0;