avoid redefinition of SET_ERRNO()

#ifdef USE_WINSOCK

#define EAFNOSUPPORT    WSAEAFNOSUPPORT

#define SET_ERRNO(e)    WSASetLastError(errno = (e))

#else

#define SET_ERRNO(e)    errno = e

#endif

/*

/*

 * Convert a network format address to presentation format.

 *

 * Returns pointer to presentation format address (`buf'),

 * Returns NULL on error (see errno).

 * Returns pointer to presentation format address (`buf').

 * Returns NULL on error and errno set with the specific

 * error, EAFNOSUPPORT or ENOSPC.

 *

 * On Windows we store the error in the thread errno, not

 * in the winsock error code. This is to avoid loosing the

 * actual last winsock error. So use macro ERRNO to fetch the

 * errno this funtion sets when returning NULL, not SOCKERRNO.

 */

char *Curl_inet_ntop(int af, const void *src, char *buf, size_t size)

{