Fix builds for g++-3.4.6,4.0.4,4.1.2, in steady-state-random-waypoint-mobility-model.cc, it calls node.create (double instead of uint32_t)

{
  Supress invalid read size errors in SendPreq() when using HwmpProtocolMac
  Memcheck:Addr8
  fun:*HwmpProtocolMac*SendPreq*
}