rxrpc: Support network namespacing

Support network namespacing in AF_RXRPC with the following changes:

 (1) All the local endpoint, peer and call lists, locks, counters, etc. are
     moved into the per-namespace record.

 (2) All the connection tracking is moved into the per-namespace record
     with the exception of the client connection ID tree, which is kept
     global so that connection IDs are kept unique per-machine.

 (3) Each namespace gets its own epoch.  This allows each network namespace
     to pretend to be a separate client machine.

 (4) The /proc/net/rxrpc_xxx files are now called /proc/net/rxrpc/xxx and
     the contents reflect the namespace.

fs/afs/ should be okay with this patch as it explicitly requires the current
net namespace to be init_net to permit a mount to proceed at the moment.  It
will, however, need updating so that cells, IP addresses and DNS records are
per-namespace also.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/Makefile b/net/rxrpc/Makefile
index b9da4d6..9c68d2f 100644
--- a/net/rxrpc/Makefile
+++ b/net/rxrpc/Makefile
@@ -19,6 +19,7 @@
 	local_event.o \
 	local_object.o \
 	misc.o \
+	net_ns.o \
 	output.o \
 	peer_event.o \
 	peer_object.o \