epicsThreadMustJoin() clear joinable flag

Clear so that repeated calls will error correctly.
Only well defined for self join.

modules/libcom/src/osi/os/RTEMS/osdThread.c

@@ -380,7 +380,8 @@ void epicsThreadMustJoin(epicsThreadId id)
         /* try to error nicely, however in all likelyhood rtems_task_get_note failed,
          * or gave us the wrong thread as we are racing thread exit.
          */
-        cantProceed("%s join not enabled for thread.\n", v->name);
+        cantProceed("%s thread not joinable.\n", v->name);
+        return;
 
     } else if(target_tid!=self_tid) {
         /* wait for target to complete */
@@ -393,6 +394,7 @@ void epicsThreadMustJoin(epicsThreadId id)
         }
     }
 
+    v->joinable = 0;
     taskUnref(v);
     /* target task may be deleted.
      * self task is not deleted, even for self join.

modules/libcom/src/osi/os/WIN32/osdThread.c

@@ -673,7 +673,8 @@ void epicsThreadMustJoin(epicsThreadId id)
          * 'pParmWIN32' has already crashed us as we are racing thread exit,
          * which free's 'pParmWIN32'.
          */
-        cantProceed("%s join not enabled for thread.\n", pParmWIN32->pName);
+        cantProceed("%s thread not joinable.\n", pParmWIN32->pName);
+        return;
 
     } else if(epicsThreadGetIdSelf() != id) {
         DWORD status = WaitForSingleObject(pParmWIN32->handle, INFINITE);
@@ -681,9 +682,11 @@ void epicsThreadMustJoin(epicsThreadId id)
             /* TODO: signal error? */
         }
 
+        pParmWIN32->joinable = 0;
         epicsParmCleanupWIN32(pParmWIN32);
     } else {
         /* join self silently does nothing */
+        pParmWIN32->joinable = 0;
         epicsParmCleanupWIN32(pParmWIN32);
     }
 }

modules/libcom/src/osi/os/posix/osdThread.c

@@ -612,7 +612,8 @@ void epicsThreadMustJoin(epicsThreadId id)
          * 'id' has already caused SIGSEGV as we are racing thread exit,
          * which free's 'id'.
          */
-        cantProceed("%s join not enabled for thread.\n", id->name);
+        cantProceed("%s thread not joinable.\n", id->name);
+        return;
     }
 
     status = pthread_join(id->tid, &ret);
@@ -623,6 +624,7 @@ void epicsThreadMustJoin(epicsThreadId id)
         status = pthread_detach(id->tid);
         checkStatusOnce(status, "pthread_detach");
     } else checkStatusOnce(status, "pthread_join");
+    id->joinable = 0;
     free_threadInfo(id);
 }