[NET]: Revert socket.h/stat.h ifdef hacks.

This reverts 57a87bb0

.

As H. Peter Anvin states, this change broke klibc and it's
not very easy to fix things up without duplicating everything
into userspace.

In the longer term we should have a better solution to this
problem, but for now let's unbreak things.

Signed-off-by: David S. Miller <davem@davemloft.net>