Use RPMDBI_INSTFILENAMES on file queries as well

Use RPMDBI_INSTFILENAMES on file queries as well

- This changes query behavior quite a bit as files with non-installed
  status are no longer returned as matches. The rationale is that
  it makes figuring out dependency issues with the "new" behavior
  more obvious (but perhaps we should have a switch to enable
  former behavior). Besides not satisfying dependencies, files with
  non-installed status are not really owned by the package, as they
  would not be removed on package removal.