Add ability for rig_set_vfo to show calling function

This will be expanded to cover other functions too

include/hamlib/rig.h

@@ -2485,9 +2485,10 @@ rig_get_mode HAMLIB_PARAMS((RIG *rig,
                             rmode_t *mode,
                             pbwidth_t *width));
 
+#define rig_set_vfo(r,v) rig_set_vfo(r,v,__builtin_FUNCTION())
 extern HAMLIB_EXPORT(int)
 rig_set_vfo HAMLIB_PARAMS((RIG *rig,
-                           vfo_t vfo));
+                           vfo_t vfo, const char *func));
 extern HAMLIB_EXPORT(int)
 rig_get_vfo HAMLIB_PARAMS((RIG *rig,
                            vfo_t *vfo));