'RELENG_7_0_0_RELEASE'.

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

skip() callback to skip over data when reading uncompressed
archives.  This gets invoked, for example, during tar -t
or tar -x with a filename argument.  The revised code
only calls [lf]seek() on regular files, instead of depending
on the kernel to return an error.

Thanks to: bde for explaining the implementation of lseek()
Thanks to: Daniel O'Connor for testing
Approved by: re (Ken Smith)
MFC after: 5 days

assume yes unless seek has previously failed, but I fear I'll have to
avoid seeks under other circumstances.  (For instance, tape drives on
FreeBSD seem to return garbage from lseek().)  Also, optimize away
zero-byte skips.

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

wrap this within #if/#else/#endif so that it will only take effect once
ARCHIVE_API_VERSION is increased (which should happen on HEAD some time
between now and when RELENG_7 is branched).

archive_private.h.

 * Use public API, don't access struct archive directly.  (People should be able to copy these into their applications as a template for custom I/O callbacks.)
 * Set "skip" only for regular files.  ("skip" allows the low-level library to catch attempts to add an archive to itself or extract over itself.)
 * Simplify the write_open functions by just calling stat() at the beginning.  Somehow, these functions had acquired some complex logic that tried to avoid the stat() call but never succeeded.

MFC after: 10 days

  * 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.  ;-)

increases performance when extracting a single entry from a large
uncompressed archive, especially on slow devices such as USB hard
drives.

Requires a number of changes:
   * New archive_read_open2() supports a 'skip' client function
   * Old archive_read_open() is implemented as a wrapper now, to
     continue supporting the old API/ABI.
   * _read_open_fd and _read_open_file sprout new 'skip' functions.
   * compression layer gets a new 'skip' operation.
   * compression_none passes skip requests through to client.
   * compression_{gzip,bzip2,compress} simply ignore skip requests.

Thanks to: Benjamin Lutz, who designed and implemented the whole thing.
   I'm just committing it.  ;-)

TODO: Need to update the documentation a little bit.

routine fails or the first read fails), invoke the client close
routine immediately so the client can clean up.  Also, don't store the
client pointers in this case, so that the client close routine can't
accidentally get called more than once.

A minor style fix to archive_read_open_fd.c while I'm here.

PR: 86453
Thanks to: Andrew Turner for reporting this and suggesting a fix.