Makefile: Avoid nonportable 'basename -a'
Makefile: Avoid nonportable 'basename -a'

'basename -a' seems be a relatively new feature of GNU coreutils that
is not available in recent Debian releases.

Resolves #505.

virtualopensystems/snabbswitch,javierguerragiraldez/snabbswitch,lukego/snabb,alexandergall/snabbswitch,wingo/snabbswitch,eugeneia/snabb,wingo/snabbswitch,heryii/snabb,pavel-odintsov/snabbswitch,justincormack/snabbswitch,aperezdc/snabbswitch,snabbco/snabb,andywingo/snabbswitch,mixflowtech/logsensor,alexandergall/snabbswitch,plajjan/snabbswitch,fhanik/snabbswitch,SnabbCo/snabbswitch,plajjan/snabbswitch,kellabyte/snabbswitch,heryii/snabb,eugeneia/snabbswitch,alexandergall/snabbswitch,wingo/snabbswitch,lukego/snabb,kbara/snabb,kbara/snabb,snabbnfv-goodies/snabbswitch,eugeneia/snabb,snabbco/snabb,fhanik/snabbswitch,Igalia/snabb,dpino/snabb,xdel/snabbswitch,wingo/snabb,fhanik/snabbswitch,javierguerragiraldez/snabbswitch,pirate/snabbswitch,snabbco/snabb,eugeneia/snabbswitch,pirate/snabbswitch,dpino/snabb,wingo/snabb,andywingo/snabbswitch,dpino/snabb,lukego/snabbswitch,wingo/snabb,aperezdc/snabbswitch,virtualopensystems/snabbswitch,lukego/snabbswitch,alexandergall/snabbswitch,dpino/snabb,pirate/snabbswitch,snabbco/snabb,SnabbCo/snabbswitch,snabbco/snabb,dwdm/snabbswitch,justincormack/snabbswitch,mixflowtech/logsensor,snabbnfv-goodies/snabbswitch,Igalia/snabbswitch,plajjan/snabbswitch,kellabyte/snabbswitch,dpino/snabb,eugeneia/snabb,dpino/snabbswitch,SnabbCo/snabbswitch,virtualopensystems/snabbswitch,Igalia/snabb,kellabyte/snabbswitch,heryii/snabb,alexandergall/snabbswitch,heryii/snabb,wingo/snabb,Igalia/snabb,snabbco/snabb,Igalia/snabbswitch,eugeneia/snabb,snabbco/snabb,xdel/snabbswitch,dpino/snabb,wingo/snabbswitch,lukego/snabb,alexandergall/snabbswitch,snabbco/snabb,eugeneia/snabb,Igalia/snabbswitch,kbara/snabb,mixflowtech/logsensor,justincormack/snabbswitch,heryii/snabb,kbara/snabb,Igalia/snabb,lukego/snabbswitch,Igalia/snabb,lukego/snabb,hb9cwp/snabbswitch,Igalia/snabbswitch,heryii/snabb,pavel-odintsov/snabbswitch,pavel-odintsov/snabbswitch,Igalia/snabb,eugeneia/snabb,Igalia/snabb,dwdm/snabbswitch,eugeneia/snabb,snabbnfv-goodies/snabbswitch,kbara/snabb,javierguerragiraldez/snabbswitch,mixflowtech/logsensor,kbara/snabb,dpino/snabbswitch,snabbnfv-goodies/snabbswitch,eugeneia/snabbswitch,justincormack/snabbswitch,andywingo/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,aperezdc/snabbswitch,dwdm/snabbswitch,dpino/snabbswitch,andywingo/snabbswitch,hb9cwp/snabbswitch,eugeneia/snabbswitch,lukego/snabbswitch,hb9cwp/snabbswitch,Igalia/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,wingo/snabb,aperezdc/snabbswitch,plajjan/snabbswitch,hb9cwp/snabbswitch,dpino/snabb,Igalia/snabbswitch,dpino/snabbswitch,mixflowtech/logsensor,wingo/snabb,xdel/snabbswitch