server: set_server_state needs to be called with non-NULL server.

Spotted by Coverity.

server/named_pipe.c

diff --git a/server/named_pipe.c b/server/named_pipe.c
index 6dba1f3..39dd10a 100644
--- a/server/named_pipe.c
+++ b/server/named_pipe.c
@@ -739,7 +739,7 @@
     if (!(server->ioctl_fd = alloc_pseudo_fd( &pipe_server_fd_ops, &server->obj, options )))
     {
         release_object( server );
-        server = NULL;
+        return NULL;
     }
     set_server_state( server, ps_idle_server );
     return server;