cc1100_phy.c: fix usage of timex_t
cc1100-csmaca-mac.c: fix usage of timex_t
flowcontrol.c: fix usage of timex_t
lowpan.c: fix usage of timex_t
destiny.c: fix usage of timex_t
tcp_timer.c: fix usage of timex_t
socket.c: fix usage of timex_t
added timex_isnormalized