delay registering second cleanupPy()

until just _before_ exitDatabase, to ensure
that cleanup happens _after_ devSup detach().

Still allows devSup build() the opportunity
to add epicsAtExit() which happen between
cac cleanup and our cleanup.

pyIocApp/setup.c

@@ -123,7 +123,7 @@ static void cleanupPrep(initHookState state)
     /* register a second time to better our chances of running
      * first on exit.  eg. before cacExitHandler()
      */
-    if(state==initHookAfterIocRunning)
+    if(state==initHookAfterInitDevSup)
         epicsAtExit(&cleanupPy, NULL);
 }