fix cloc, filemap, list-owners and changed when they come across deferred_sources

Travis CI: https://travis-ci.org/pantsbuild/pants/builds/128563441
This should fix the error:

Exception message: Field requires a call to populate() before this method can be called.


When calling changed, cloc, filedep or list-owners on a target that depends on a deferred_source target
It seemed like having the tasks require deferred_sources in a prepare method would be the better way to fix this 

  @classmethod
  def prepare(cls, options, round_manager):
      ...
    round_manager.require_data('deferred_sources')


But that only worked for cloc, and did not work for the failing test in cloc