Fix ST command for older FTDX101D/MP firmware -- needed to turn on split light

Apparenlty split was still working but light was not coming on.
https://github.com/Hamlib/Hamlib/issues/1388

rigs/yaesu/newcat.c

@@ -7917,14 +7917,17 @@ int newcat_set_tx_vfo(RIG *rig, vfo_t tx_vfo)
         if (rig->state.current_vfo == RIG_VFO_B || rig->state.current_vfo == RIG_VFO_SUB) { p1++; }
     }
 
-#if 0 // this doesn't seem to work on FTDX101MP latest firmware as of 20230911
-    if ((is_ftdx101d || is_ftdx101mp) && p1 == '1')
+    // this doesn't seem to work on FTDX101MP latest firmware as of 20230911 so we test once and disable if needed
+    if ((is_ftdx101d || is_ftdx101mp) && p1 == '1' && !priv->ftdx101_st_missing)
     {
         // what other Yaesu rigs should be using this?
         // The DX101D returns FT0 when in split and not transmitting
         command = "ST";
+        SNPRINTF(priv->cmd_str, sizeof(priv->cmd_str), "%s%c%c", command, p1, cat_term);
+        int retval = newcat_set_cmd(rig);
+        if (retval != RIG_OK) {priv->ftdx101_st_missing = 1;retval=RIG_OK;}
+        RETURNFUNC(retval);
     }
-#endif
 
     SNPRINTF(priv->cmd_str, sizeof(priv->cmd_str), "%s%c%c", command, p1, cat_term);
 

rigs/yaesu/newcat.h

@@ -129,6 +129,7 @@ struct newcat_priv_data
     int poweron; /* to prevent powering on more than once */
     int question_mark_response_means_rejected; /* the question mark response has multiple meanings */
     char front_rear_status; /* e.g. FTDX5000 EX103 status */
+    int ftdx101_st_missing; /* is ST command gone?  assume not until proven otherwise */
 };
 
 /*