[BusyBox] update to my tar.c

[Glenn]

I got around to fixing a few more bugs with my tar code that is aiming to
replace the extraction code in tar.c with untar code from libb/unarchive.c

http://people.debian.org/~bug1/busybox/tar.c.0804
or
http://people.debian.org/~bug1/busybox/tar.c.0804.diff

Changes between my code and the official code are

Good
 - Use common code from ./libb/unarchive.c which is used by dpkg-deb to
untar
 - Supports the -T option to exclude a list of files
 - Its 1.5kB smaller with a defualt build (but note below for some misisng
functionality), saving more if you use ar, cpio dpkg-deb or dpkg as well.
 - I just tested all the extraction functions and cant find any bugs
(famous last words)

Bad
 - I havent implemented any recent changes to official bb tar.c, include
2k bs and long getopts.
 - Havent tested to tar creation code for a while


Glenn