user: Implementation of Get/SetWindowLongPtr for 64-bit platforms.

Also use the same code for Get/SetWindowWord.
Based on a patch by Ge van Geldorp.
diff --git a/server/trace.c b/server/trace.c
index 574943a..c5248fe 100644
--- a/server/trace.c
+++ b/server/trace.c
@@ -2372,7 +2372,7 @@
     fprintf( stderr, " user_data=%p,", req->user_data );
     fprintf( stderr, " extra_offset=%d,", req->extra_offset );
     fprintf( stderr, " extra_size=%u,", req->extra_size );
-    fprintf( stderr, " extra_value=%08x", req->extra_value );
+    fprintf( stderr, " extra_value=%lx", req->extra_value );
 }
 
 static void dump_set_window_info_reply( const struct set_window_info_reply *req )
@@ -2382,7 +2382,7 @@
     fprintf( stderr, " old_id=%08x,", req->old_id );
     fprintf( stderr, " old_instance=%p,", req->old_instance );
     fprintf( stderr, " old_user_data=%p,", req->old_user_data );
-    fprintf( stderr, " old_extra_value=%08x", req->old_extra_value );
+    fprintf( stderr, " old_extra_value=%lx", req->old_extra_value );
 }
 
 static void dump_set_parent_request( const struct set_parent_request *req )