- also remove backup files (*.bak) on "clean" target

- remove the (for a long-time) obsolete "dist.tar" target
  because we already use the step-by-step document for
  building releases and this particular "dist.tar" target
  is at least broken because of the changed subdir/files tree


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@80231 13f79535-47bb-0310-9956-ffa450edef68