Log Message:
Update dictbb to 0.48.0

  Fix distbb_chroot script.

  Minor fix in stage_gen_report for better conformance to
  HTML-4.01/strict

  Update default config file distbb.conf.

  Update README.

  Use native targets "clean" and "package" in unprivileged \ 
mode (if
  UNPRIV_USER is set) instead of home-made "Clean" and "Package".

  Set LD_PRELOAD and LIBKVER_OSRELEASE only on slave hosts.

  Introduce new configuration variables OS_VERSION and MACHINE_ARCH.

  Add new target CleanupPkgdb to TARGETS.

  Add new configuration variable SLAVE_CMD

  Configuration variable PKGSRCVER defaults to unknown.

  Add $PKGSRCVER to report.html.

  Minor clean-ups in "distbb_chroot", "distbb.conf",
  "distbb.default.conf", "slave" and "common" \ 
configs and scripts.