update version to 3.8
update version to 3.8

The merge window is going to close soon so
release version 3.8 with nl80211.h from that
tree.

bw-oss/iw,Distrotech/iw,cozybit/iw,Distrotech/iw,CTU-IIG/802.11p-iw,greearb/iw-ct,greearb/iw-ct,CTU-IIG/802.11p-iw,chunyeow/iw,bw-oss/iw,chunyeow/iw,cozybit/iw