use struct ptr for ID types because:

o this is more type safe
o this works better with source level debuggers

src/libCom/test/epicsEventTest.cpp

@@ -55,7 +55,7 @@ static void consumer(void *arg)
                 idSelf,(int)status,time(&tp));
         }
         while(epicsRingPointerGetUsed(pinfo->ring)>=2) {
-            epicsThreadId message[2];
+            epicsRingPointerId message[2];
             int i;
 
             for(i=0; i<2; i++) {