'RELENG_7_0_0_RELEASE'.

This commit was manufactured to restore the state of the 7.0-RELEASE image.

Thanks to: Joerg Sonnenberger

  * libarchive_test program exercises many of the core features
  * Refactored old "read_extract" into new "archive_write_disk", which
    uses archive_write methods to put entries onto disk.  In particular,
    you can now use archive_write_disk to create objects on disk
    without having an archive available.
  * Pushed some security checks from bsdtar down into libarchive, where
    they can be better optimized.
  * Rearchitected the logic for creating objects on disk to reduce
    the number of system calls.  Several common cases now use a
    minimum number of system calls.
  * Virtualized some internal interfaces to provide a clearer separation
    of read and write handling and make it simpler to override key
    methods.
  * New "empty" format reader.
  * Corrected return types (this ABI breakage required the "2.0" version bump)
  * Many bug fixes.

a vanilla 2-clause BSD license, but somehow some confusing
extra verbage get copied from somewhere.

Also, update the copyright dates to 2007 for all of the files.

Prompted by: several questions about what those extra words really mean

file.  This doesn't happen in normal use, because the file I/O and
decompression layers only pass through smaller blocks.  It can happen
with custom read functions that block I/O in larger blocks.

  * Actually use the HAVE_<header>_H macros to conditionally include
    system headers.  They've been defined for a long time, but only
    used in a few places.  Now they're used pretty consistently
    throughout.
  * Fill in a lot of missing casts for conversions from void*.
    Although Standard C doesn't require this, some people have been
    trying to use C++ compilers with this code, and they do require it.

Bit-for-bit, the compiled object files are identical, except for
one assert() whose line number changed, so I'm pretty confident I
didn't break anything.  ;-)

content of an archive entry to a file descriptor.

compiling on IRIX and Solaris.  Remove the "archive_check_magic" macro
that existed only to provide __func__ to the underlying __archive_check_magic
function.

Thanks to: Darin Broady
MFC after: 14 days

This change also pointed out one API deficiency: the
archive_read_data_into_XXX functions were originally defined to return
the total bytes read.  This is, of course, ambiguous when dealing with
non-contiguous files.  Change it to just return a status value.