wext: Emit event stream entries correctly when compat.

Three major portions to this change:

1) Add IW_EV_COMPAT_LCP_LEN, IW_EV_COMPAT_POINT_OFF,
   and IW_EV_COMPAT_POINT_LEN helper defines.

2) Delete iw_stream_check_add_*(), they are unused.

3) Add iw_request_info argument to iwe_stream_add_*(), and use it to
   size the event and pointer lengths correctly depending upon whether
   IW_REQUEST_FLAG_COMPAT is set or not.

4) The mechanical transformations to the drivers and wireless stack
   bits to get the iw_request_info passed down into the routines
   modified in #3.  Also, explicit references to IW_EV_LCP_LEN are
   replaced with iwe_stream_lcp_len(info).

With a lot of help and bug fixes from Masakazu Mokuno.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/wireless.h b/include/linux/wireless.h
index 79d8468..d7958f9 100644
--- a/include/linux/wireless.h
+++ b/include/linux/wireless.h
@@ -1113,6 +1113,21 @@
 #define IW_EV_POINT_LEN	(IW_EV_LCP_LEN + sizeof(struct iw_point) - \
 			 IW_EV_POINT_OFF)
 
+#ifdef __KERNEL__
+#ifdef CONFIG_COMPAT
+struct __compat_iw_event {
+	__u16		len;			/* Real length of this stuff */
+	__u16		cmd;			/* Wireless IOCTL */
+	compat_caddr_t	pointer;
+};
+#define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer)
+#define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length)
+#define IW_EV_COMPAT_POINT_LEN	\
+	(IW_EV_COMPAT_LCP_LEN + sizeof(struct compat_iw_point) - \
+	 IW_EV_COMPAT_POINT_OFF)
+#endif
+#endif
+
 /* Size of the Event prefix when packed in stream */
 #define IW_EV_LCP_PK_LEN	(4)
 /* Size of the various events when packed in stream */