WorkStruct: Separate delayable and non-delayable events.

Separate delayable work items from non-delayable work items be splitting them
into a separate structure (delayed_work), which incorporates a work_struct and
the timer_list removed from work_struct.

The work_struct struct is huge, and this limits it's usefulness.  On a 64-bit
architecture it's nearly 100 bytes in size.  This reduces that by half for the
non-delayable type of event.

Signed-Off-By: David Howells <dhowells@redhat.com>
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 7ccfc7e..95796e6 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -51,7 +51,7 @@
 
 	unsigned long		cl_lease_time;
 	unsigned long		cl_last_renewal;
-	struct work_struct	cl_renewd;
+	struct delayed_work	cl_renewd;
 
 	struct rpc_wait_queue	cl_rpcwaitq;