Update jbigkit to 2.1.

Changes in version 2.1 (2014-04-08)

This is a security-critical bug-fix release that remains API and ABI
backwards compatible to version 2.0. Users who process BIE data from
untrusted sources should upgrade.

  - fixed a buffer-overflow vulnerability in the jbig.c decoder,
    reported by Florian Weimer (Red Hat): CVE-2013-6369

  - fixed ability of corrupted input data to force jbig85.c decoder
    into an end-less loop

  - fixed a bug in the processing of private deterministic-prediction
    tables (DPPRIV=1) in jbig.c decoder

  - fixed integer-type mismatches in printf arguments on 64-bit systems

  - fuzz-testing script added

(obache)