Changing testrigcaps to give a warning on power_max instead of an error

Added comments to rig_state explain fragility of shared library effects
vfo_list is the only known item that really matters to if that changes it will fail make check
https://github.com/Hamlib/Hamlib/issues/581

include/hamlib/rig.h

@@ -2124,8 +2124,9 @@ struct rig_cache {
  * This struct contains live data, as well as a copy of capability fields
  * that may be updated (ie. customized)
  *
- * It is fine to move fields around, as this kind of struct should
- * not be initialized like caps are.
+ * It is NOT fine to move fields around as it can break share library offset
+ * As of 2021-03-03  vfo_list is the last known item being reference externally
+ * So any additions or changes to this structure must be after vfo_list.
  */
 struct rig_state {
     /*
@@ -2188,6 +2189,8 @@ struct rig_state {
     pbwidth_t current_width;    /*!< Passband width currently set */
     vfo_t tx_vfo;               /*!< Tx VFO currently set */
     rmode_t mode_list;              /*!< Complete list of modes for this rig */
+    // mode_list is used by some 
+    // so anything added to this structure must be below here
     int transmit;               /*!< rig should be transmitting i.e. hard
                                      wired PTT asserted - used by rigs that
                                      don't do CAT while in Tx */

tests/testrigcaps.c

@@ -12,7 +12,7 @@ int main()
     void *p1 = &rig->state.rigport;
     void *p2 = &rig->state.vfo_list;
     unsigned long offset = p2 - p1;
-    printf("offset vfo_list=%lu\n", offset);
+    printf("offset vfo_list=%lu -- this is the important one\n", offset);
 #if defined(WIN64) || defined (_WIN64) || defined (__WIN64__)
     int expected = 13264; // mingw64
 #elif defined(WIN32) || defined (_WIN32) || defined(__WIN32__)
@@ -50,9 +50,9 @@ int main()
 
     if (offset != expected)
     {
-        printf("offset of power_max has changed!!!\n");
+        printf("Warning...offset of power_max has changed!!!\n");
         printf("was %d, now %lu\n", expected, offset);
-        retcode = 1;
+        retcode = 0;
     }
 
     return retcode;