Cygwin: asm/socket.h: drop outdated casts

Cygwin: asm/socket.h: drop outdated casts

The _IOR anbd _IOW macros cast the sizeof of their third arg
uselessly to long. The _IO definitions have been taken from BSD
in 1995 and never changed again.  The fact that the sizeof() gets
cast to long is probably a remnant from the past when the stuff
was supposed to be used on 16 bit machines, but the value was
supposed to be 32 bit.

Given that the values are not supposed to be ever bigger than 32 bit,
we drop the (long) cast.  Compare with current FreeBSD, which does
not cast at all.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>