8066199: C2 escape analysis prevents VM from exiting quickly

Summary: Check for safepoint and block during EA Connection graph construction.
Reviewed-by: roland, vlivanov, shade

src/share/vm/opto/escape.cpp

@@ -1106,6 +1106,9 @@ bool ConnectionGraph::complete_connection_graph(
           // Each 4 iterations calculate how much time it will take
           // to complete graph construction.
           time.stop();
+          // Poll for requests from shutdown mechanism to quiesce compiler
+          // because Connection graph construction may take long time.
+          CompileBroker::maybe_block();
           double stop_time = time.seconds();
           double time_per_iter = (stop_time - start_time) / (double)SAMPLE_SIZE;
           double time_until_end = time_per_iter * (double)(java_objects_length - next);