Don't get iw version from git if there is no .git/
Don't get iw version from git if there is no .git/

The version.sh script should only try to get the version from git if the
source actually resides in a git repository, i.e. .git/ exists. Doing
otherwise in a non-git source repo results in git ascending until it
finds a .git directory, which will cause problems in some source-based
distributions ( https://bugs.gentoo.org/show_bug.cgi?id=482334 ).

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