symlink: generalized follow_link()

no longer depends on nfs41_open_state or open_upcall_args
renamed to nfs41_symlink_follow() and added prototype to nfs41_ops.h

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>

daemon/open.c

@@ -265,7 +265,8 @@ int handle_open(nfs41_upcall *upcall)
                 upcall->last_error = ERROR_REPARSE;
 
                 /* replace the path with the symlink target */
-                status = follow_link(args, state);
+                status = nfs41_symlink_follow(state->session,
+                    &state->parent, &state->file, &args->symlink);
                 goto out_free_state;
             }
         } else