8234009: ZGC: Move resurrection unblock to before the _unload.purge() call

Reviewed-by: pliden, eosterlund

src/hotspot/share/gc/z/zHeap.cpp

@@ -352,12 +352,12 @@ void ZHeap::process_non_strong_references() {
   ZRendezvousClosure cl;
   Handshake::execute(&cl);
 
-  // Purge stale metadata and nmethods that were unlinked
-  _unload.purge();
-
   // Unblock resurrection of weak/phantom references
   ZResurrection::unblock();
 
+  // Purge stale metadata and nmethods that were unlinked
+  _unload.purge();
+
   // Enqueue Soft/Weak/Final/PhantomReferences. Note that this
   // must be done after unblocking resurrection. Otherwise the
   // Finalizer thread could call Reference.get() on the Finalizers