proper types to use for getnameinfo args

proper types to use for getnameinfo args

target use calling convention WSAAPI for getnameinfo() prototype.
Checking type DWORD as argument 4 and 6 of getnameinfo not needed.

following order: 'struct sockaddr *' 'const struct sockaddr *' 'void *'.

Avoid breaking configure due to CURL_FUNC_GETNAMEINFO_ARGTYPES failure, since at this point nothing depends on it.

justify checking for socklen_t in more than one function, the code
used to find a valid socklen_t replacement is simplified back. The
only function that will be used to find a socklen_t replacement is
getpeername, as it has been since revision 1.4 of curl/acinclude.m4

CURL_FUNC_GETNAMEINFO_ARGTYPES now also checks first argument.
All related changes taken to cares configuration scripts.

Added constants that will be used by ares_getaddrinfo. Made ares_getnameinfo use the reentrant getservbyport (getservbyport_r) if it isavailable to ensure it works properly in a threaded environment

inventing and providing our own. Hopefully this solves a HP-UX 11.00 problem.

  Make UDP sockets non-blocking. I've confirmed that at least on Linux 2.4 a
  read event can come back from poll() on a valid SOCK_DGRAM socket but
  recv(2) will still block. This patch doesn't ignore EAGAIN in
  read_udp_packets(), though maybe it should. (This patch was edited by Daniel
  Stenberg and a new configure test was added (imported from curl's configure)
  to properly detect what non-blocking socket approach to use.)

work fine with cross-compiled builds.

first little steps towards IPv6 support!

configure stuff