coverity#704551 Dereference after null check

Change-Id: I47aa14ba58d993fa8ed20c8f0d99e92f18dc53e6
Reviewed-on: https://gerrit.libreoffice.org/2214Reviewed-by: Andras Timar <atimar@suse.com>
Tested-by: Andras Timar <atimar@suse.com>

avmedia/source/framework/mediacontrol.cxx

@@ -559,7 +559,10 @@ IMPL_LINK( MediaControl, implSelectHdl, ToolBox*, p )
     }
 
     update();
-    p->Invalidate( INVALIDATE_UPDATE );
+    if(p)
+    {
+        p->Invalidate( INVALIDATE_UPDATE );
+    }
 
     return 0;
 }