update custom callbacks to properly exit thread on disconnect

GameFiles/IW4x/userraw/scripts/_customcallbacks.gsc

@@ -144,6 +144,7 @@ waitForFrameThread()
 
 waitForAdditionalAngles( logString, beforeFrameCount, afterFrameCount )
 {
+    self endon( "disconnect" );
 	currentIndex = self.currentAnglePosition;
 	wait( 0.05 * afterFrameCount );
 	
@@ -253,4 +254,4 @@ Callback_PlayerDisconnect()
 {
 	level notify( "disconnected", self );
 	self maps\mp\gametypes\_playerlogic::Callback_PlayerDisconnect();
-}
+}