add (untested) implementation of sendmsg in terms of WSASendMsg
Windows does not support in_pktinfo.ipi_spec_dst
set the include flag for windows compat headers in configure
socket.c needs closesocket from internal.h
add ioctl as a wrapper around ioctlsocket
avoid pointer type warnings from setsockopt
on Windows this argument is not marked const
silence "unused parameter" warning
work around lack of fcntl on Windows