netlink_route_socket: add new nlmsg_readpriv perm

Used when mapping RTM_GETLINK messages to this new permission.

Users of netlink_route_sockets that do not use the net_domain()
macro will need to grant this permission as needed. Compatibility
with older vendor images is preserved by granting all vendor domains
access to this new permission in *.compat.cil files.

Bug: 141455849
Test: build (this change is a no-op without kernel changes)
Change-Id: I18f1c9fc958120a26b7b3bea004920d848ffb26e
diff --git a/private/access_vectors b/private/access_vectors
index 275b9af..66c1b79 100644
--- a/private/access_vectors
+++ b/private/access_vectors
@@ -446,6 +446,7 @@
 {
 	nlmsg_read
 	nlmsg_write
+	nlmsg_readpriv
 }
 
 class netlink_tcpdiag_socket