rcv_wscale is a symetric parameter with snd_wscale.

Both this parameters are set on a connection handshake.

Without this value a remote window size can't be interpreted correctly,
because a value from a packet should be shifted on rcv_wscale.

This patch doesn't break a back compatibility, a rcv window
will be restored with the same bug (rcv_wscale = 0).

v2: Update to a new kernel interface:
	[PATCH] tcp: restore rcv_wscale in a repair mode (v2)
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>