Add /usr/sbin to path when looking for varnishd.
Add /usr/sbin to path when looking for varnishd.

wjordan/libvmod-cookie,varnish/libvmod-cookie,tricycle/libvmod-cookie,wjordan/libvmod-cookie,lkarsten/libvmod-cookie,ruckserve/libvmod-cookie,lkarsten/libvmod-cookie,varnish/libvmod-cookie,ruckserve/libvmod-cookie,tricycle/libvmod-cookie