Back-patch creation of tar.bz2 tarball during "make dist".

Back-patch creation of tar.bz2 tarball during "make dist".

Since commit a4d03bbcdaf7739d7e9073ee76bb186f68ddc163, "make dist" has
built both gzip- and bzip2-compressed tarballs.  However, this was
pretty useless, because our tarball build script didn't know about it
and proceeded to overwrite the bz2 file with new data.  Back-patch the
change to all active branches, so that creation of the tar.bz2 file
can be removed from the build script.