Add sys/time.h include to enable build on FreeBSD

https://github.com/Hamlib/Hamlib/issues/869

include/hamlib/rig.h

@@ -32,6 +32,7 @@
 #include <string.h>
 #include <inttypes.h>
 #include <time.h>
+#include <sys/time.h>
 
 /* Rig list is in a separate file so as not to mess up w/ this one */
 #include <hamlib/riglist.h>