client: fix behavior of walking where there are no tiles

This only happens with a plugin force setting checkClick. This would
cause the client to possibly incorrectly send a walk packet next tick if
viewportWalking was set, since nothing ever clears it.

runescape-api/src/main/java/net/runelite/rs/api/RSClient.java

@@ -140,7 +140,6 @@ public interface RSClient extends RSGameEngine, Client
 	int getRSGameState();
 
 	@Import("checkClick")
-	@Override
 	void setCheckClick(boolean checkClick);
 
 	@Import("mouseX2")
@@ -1007,4 +1006,7 @@ public interface RSClient extends RSGameEngine, Client
 
 	@Import("soundEffectVolume")
 	int getSoundEffectVolume();
+
+	@Import("viewportWalking")
+	void setViewportWalking(boolean viewportWalking);
 }