configure: get latest git rev from HEAD not from master.
configure: get latest git rev from HEAD not from master.

In tags there's no 'master' branch so use HEAD instead.

datenwolf/xbps,ebfe/xbps,stpx/xbps,stpx/xbps,ebfe/xbps,datenwolf/xbps,datenwolf/xbps,ebfe/xbps,stpx/xbps