Disable execution timeouts for now.

This is a quick hack to disable the execution timeout, while still
making the application able to exit if the window is requested to close.
Execution limits may be reintroduced with more debugging features, but
not enabled by default.

src/uxnemu.c

@@ -466,7 +466,7 @@ run(Uxn *u)
 int
 uxn_interrupt(void)
 {
-	return ((Sint64)(exec_deadline - SDL_GetPerformanceCounter())) > 0;
+	return !SDL_QuitRequested();
 }
 
 int