Our API usage requires Vista, set WIN32_LEAN_AND_MEAN to fix a number
of issues (winsock2.h include order for ex, which is better to include
first for legacy reasons).
While at it, group redundants #ifndef _WIN32 blocks.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>