res_gethostbyname
if ((hp2 = res_gethostbyname(hbuf)) != (struct hostent *)NULL)
#define gethostbyname res_gethostbyname /* libnsl */
if (res_gethostbyname == 0) {
extern struct hostent *res_gethostbyname(const char *);
#define gethostbyname res_gethostbyname