Log Message:
update clamav to 0.87.1.

changes since 0.87:

  * Bugfixes:
    - libclamav/petite.c: fix boundary checks (acab)
    - libclamav/mbox.c: scan attachments that have no filename (njh)
    - libclamav/fsg.c: fix buffer size calculation in unfsg_133
      Reported by Zero Day Initiative (ZDI-CAN-004)
    - libclamav/tnef.c: fix possible infinite loop
      Reported by iDEFENSE (IDEF1169).
    - libclamav/mspack/cabd.c: fix possible infinite loop in cabd_find
      (tk)
      Reported by iDEFENSE (IDEF1180).
    - clamd/others.c: fix compilation error on Cobalt Qube 1 (tk)
    - clamd: properly handle ReadTimeout in SESSION (tk)
      Bug reported by Kamil Kaczkowski <kamil*kamil.eisp.pl>
    - libclamav/others.c,h: Add generic bitset implementation (trog)
    - libclamav/ole2_extract.c: Make sure the property tree doesn't
      loop (trog)
      Fixes CAN-2005-3239. Installations with default settings were
      not affected by this bug.