Don't attempt to stop threads on exit

With IL2CPP, we don't have a good way to stop managed threads. So let's
just ignore that and exit the process.

This won't clean up and run finalizers, but the process it ending
anyway, so we don't care too much.

Author: Josh Peterson

mono/mini/debugger-agent.c

@@ -8753,12 +8753,20 @@ vm_commands (int command, int id, guint8 *p, guint8 *end, Buffer *buf)
 
 			mono_environment_exitcode_set (exit_code);
 
+			/*
+			 * We don't have a good way to suspend threads in IL2CPP, so just
+			 * skip this code and call exit below. We will not shut down cleanly
+			 * (e.g. run finalizers) but we don't care too much about that with
+			 * IL2CPP.
+			*/
+#ifndef RUNTIME_IL2CPP
 			/* Suspend all managed threads since the runtime is going away */
 			DEBUG_PRINTF (1, "Suspending all threads...\n");
 			mono_thread_suspend_all_other_threads ();
 			DEBUG_PRINTF (1, "Shutting down the runtime...\n");
 			mono_runtime_quit ();
 			transport_close2 ();
+#endif
 			DEBUG_PRINTF (1, "Exiting...\n");
 
 			exit (exit_code);