bZip2 recompression broken

[schnaader]

The file "samba" from the Silesia corpus contains 7 bZip2 streams which are not processed correctly anymore, most likely due to the 64 bit stream size changes.

Precomp 0,4.6 -t+b: 7/7 bZip2 streams
Precomp 0.4.7dev -t+b: 2/7 bZip2 streams

There was a display bug in -v mode in 0.4.6 (compressed size shown as -1), but the streams were processed correctly anyway. In 0.4.7dev, five are reported as "can be decompressed as 0 bytes" and skipped, the other two have a "match" of only 10 compressed bytes (correct compressed sizes would be 2727 and 3051 bytes).