Recognise Lustre as a remote file system (#4530)

Lustre is also a remote file system that wants the network to be up before it is mounted.

src/basic/mount-util.c

@@ -525,6 +525,7 @@ bool fstype_is_network(const char *fstype) {
                 "glusterfs\0"
                 "pvfs2\0" /* OrangeFS */
                 "ocfs2\0"
+                "lustre\0"
                 ;
 
         const char *x;