git: Update to libarchive-2.8.4.

[Matthew Dillon]

:commit cacb2790a424e3d5000d44f8aed3d9e0bc5b940c
:Author: Peter Avalos <pavalos at dragonflybsd.org>
:Date:   Sun Dec 19 01:46:45 2010 -1000
:
:    Update to libarchive-2.8.4.
:    
:    This includes support for lzma and no longer relies on OpenSSL for hash
:    functions.

    I think this broke our snapshot builds.  The pkgsrc bootstrap is no
    longer working, something about missing lzma symbols/procedures.

    >  /usr/lib/libarchive.so: undefined reference to `lzma_lzma_preset'
    >  /usr/lib/libarchive.so: undefined reference to `lzma_stream_decoder'
    ...

    I don't see any lzma functions in the libarchive commit at all.

						-Matt