travis: ensure 'make install' doesn't fail
travis: ensure 'make install' doesn't fail

Signed-off-by: Aleksandr Mezin <76c1e6be84a1d2145428706eb61f38549c50daf3@gmail.com>

ysbnim/lxc,hallyn/lxc,thmo/lxc,terceiro/lxc,hallyn/lxc,GreatFruitOmsk/lxc,federicobriata/lxc,cjwatson/lxc,caglar10ur/lxc,ysbnim/lxc,ysbnim/lxc,hfuCN/lxc,ss1h2a3tw/lxc,QingweiPeterLan/cs188-lxc,QingweiPeterLan/cs188-lxc,LynxChaus/lxc,thmo/lxc,hfuCN/lxc,caglar10ur/lxc,QingweiPeterLan/cs188-lxc,ss1h2a3tw/lxc,aeris/lxc,cjwatson/lxc,federicobriata/lxc,LynxChaus/lxc,aeris/lxc,LynxChaus/lxc,terceiro/lxc,hallyn/lxc,cjwatson/lxc,federicobriata/lxc,GreatFruitOmsk/lxc,aeris/lxc,thmo/lxc,ss1h2a3tw/lxc,terceiro/lxc,hfuCN/lxc,GreatFruitOmsk/lxc,caglar10ur/lxc