fixed crash when leaving empty message

git-svn-id: http://svn.berlios.de/svnroot/repos/sems/trunk@853 8eb893ce-cfd4-0310-b710-fb5ebe64c474

apps/voicemail/AnswerMachine.cpp

@@ -821,6 +821,7 @@ void AnswerMachineDialog::saveBox(FILE* fp) {
   di_args.push(df);  
   msg_storage->invoke("msg_new",di_args,ret);  
   // TODO: evaluate ret return value
-  fclose(fp);
+  if (fp)
+    fclose(fp);
 }