(Win32) Fix socket options. Use env variable to Bonjour SDK path

[fduncanh]

this is what ludimus did

#ifdef WIN32
#include <winsock2.h>
#define TCP_KEEPALIVE 3
#define TCP_KEEPCNT 16
#define TCP_KEEPIDLE TCP_KEEPALIVE
#define TCP_KEEPINTVL 17
#else

so you agree. for KEEPCNT and KEEPINTVL

[fduncanh]

closing, your work is now added to main branch thanks