* Get rid of appending -lbz2 and -lz to ExtraLibs now that we don't need
  them any more.
* Fix the dist-check target so that EXTRA_DIST can be defined AFTER the
  include of Makefile.common. This is needed because Makefile.common
  provides variable definitions that may need to be used in computing the
  value of EXTRA_DIST.
* Clean up some "distdir" target output.

llvm-svn: 18329