Build demo TCP project using MinGW

I have modified pcap-stdinc.h as follows

#ifdef _MSC_VER
#if _MSC_VER < 1500
#define snprintf _snprintf
#define vsnprintf _vsnprintf
#define strdup _strdup
#endif
#endif

with this change I can compile without errors.

but I don’t see any UDP traffic on 192.168.220.192