*problem
1. Firt time to execute "bitbake apt-native", apt.conf.sample is created.
2. Execute "bitbake apt-native -ccleansstate", apt.conf.sample is not removed.
3. Remove apt.conf.sample by hand and then execute "bitbake apt-native",
   apt.conf.sample is not created any more.

*analysis
1.The task of "do_install_config" incorrectly use "os.path.join" to create
  dir of "outdir" which is used to keep "apt.conf.sample". 

2.The rule to create "apt.conf.sample" is by the existance of "outdir", 
  not the file itself.

*solution
1. Remove "/" of sysconfdir.
2. To create "apt.conf.sample" if it doesn't exist.