add function get_xaddr() - for process option --xaddr
add function get_xaddr() - for process option --xaddr

This function converts the template parameter (option) --xaddr
to final URL for the ONVIF service. If this option is specified on the command line
does not contain a template parameter %s function snprintf() just make a copy in a static array.
If option contains template parameter %s, it will be replaced by
IP addres of Network interface specified by --if_name option.

Example:
 ./wsdd --xaddr "http://192.168.1.1:2000/onvif/device_service" - will not be changed

 ./wsdd --xaddr "http://%s:2000/onvif/device_service" --if_name eth1
 template %s will be replaced to the IP address of the network interface eth1

KoynovStas/wsdd,KoynovStas/wsdd