lsusb command crashes with segfault.

Issue

• lsusb command crashes with segfault.

  # gdb  -c core.lsusb
  Core was generated by `lsusb -t'.
  Program terminated with signal 11, Segmentation fault.
  #0  sort_busses () at lsusb-t.c:612
  612           while (p->next) {
  Missing separate debuginfos, use: debuginfo-install glibc-2.17-78.el7.x86_64
  
  (gdb) bt
  #0  sort_busses () at lsusb-t.c:612
  #1  lsusb_t () at lsusb-t.c:667
  #2  0x0000000000401ba0 in main (argc=2, argv=0x7fffdfd27a38) at lsusb.c:4045
  
  (gdb) frame 0
  #0  sort_busses () at lsusb-t.c:612
  612           while (p->next) {
  
  (gdb) list
  607       int swapped;
  608       do {
  609           p = usbbuslist;
  610           pp = &usbbuslist;
  611           swapped = 0;
  612           while (p->next) {
  613               if (p->busnum < p->next->busnum) {
  614                   t = p->next;
  615                   p->next = t->next;
  616                   t->next = p;
  
  (gdb) p p
  $1 = (struct usbbusnode *) 0x0
  
  (gdb) p p->next
  Cannot access memory at address 0x0