MAINT-7671 display_startup() was called twice per frame on login screen

indra/newview/llstartup.cpp

@@ -830,7 +830,8 @@ bool idle_startup()
 
 		// Don't do anything.  Wait for the login view to call the login_callback,
 		// which will push us to the next state.
-		display_startup();
+
+		// display() function will be the one to run display_startup()
 		// Sleep so we don't spin the CPU
 		ms_sleep(1);
 		return FALSE;