Upgrade to libbcc 0.9.0

[jasonk000]

Current Dockerfile does not build since libbcc has been updated to 0.9.0 upstream.

I propose updating ebpf_exporter to use 0.9.0.

ubuntu@ip-100-66-117-245:~/ebpf_exporter$ git checkout upstream/master 
ubuntu@ip-100-66-117-245:~/ebpf_exporter$ make
..
Step 2/4 : RUN apt-get update &&
     apt-get install -y apt-transport-https &&
     apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 648A4A16A23015EEF4A66B8E4052245BD4284CDD &&
     echo "deb https://repo.iovisor.org/apt/xenial xenial main" > /etc/apt/sources.list.d/iovisor.list &&
     apt-get update &&
     apt-get install -y libbcc=0.8.0-1 linux-headers-amd64
..
E: Version '0.8.0-1' for 'libbcc' was not found