python-lxc: follow global rpath setting for autotools builds
python-lxc: follow global rpath setting for autotools builds

When LXC is configured with --enable-rpath, I expect Python bindings
to be able to find the library in a non-standard location, just like
LXC command-line tools.

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

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