server: free strduped port numbers

Although the leak is negligible, the clean heap on exit will ease
valgrind testing.

Change-Id: I3a7a9c8e8dc7557aa51d0b9caa244537e5e7007d
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/4410
Tested-by: jenkins

src/server/server.c

@@ -641,6 +641,13 @@ int server_quit(void)
 	return last_signal;
 }
 
+void server_free(void)
+{
+	tcl_service_free();
+	telnet_service_free();
+	jsp_service_free();
+}
+
 void exit_on_signal(int sig)
 {
 #ifndef _WIN32