Move the exit code setting back after try_shutdown

This reverts part of 78cc586d935f2009058602f2bd9adedca1442442, now that
`mono_runtime_try_shutdown` does not actually shut down, but instead
does nothing with IL2CPP.

Author: Josh Peterson

mono/mini/debugger-agent.c

@@ -8750,11 +8750,11 @@ vm_commands (int command, int id, guint8 *p, guint8 *end, Buffer *buf)
 			while (suspend_count > 0)
 				resume_vm ();
 
-			mono_environment_exitcode_set (exit_code);
-			
 			if (!mono_runtime_try_shutdown ())
 				break;
 
+			mono_environment_exitcode_set (exit_code);
+
 			/* Suspend all managed threads since the runtime is going away */
 			DEBUG_PRINTF (1, "Suspending all threads...\n");
 			mono_thread_suspend_all_other_threads ();