Change cursor API to use RGBA data

This will allow us to use better formats that preserve the entire
alpha channel.
diff --git a/common/rfb/VNCSConnectionST.cxx b/common/rfb/VNCSConnectionST.cxx
index 74c40d1..e7a5dcf 100644
--- a/common/rfb/VNCSConnectionST.cxx
+++ b/common/rfb/VNCSConnectionST.cxx
@@ -1119,7 +1119,7 @@
   if (state() != RFBSTATE_NORMAL)
     return;
 
-  cp.setCursor(server->cursor);
+  cp.setCursor(*server->cursor);
 
   if (!writer()->writeSetCursor()) {
     if (!writer()->writeSetXCursor()) {