[BusyBox] LZMA (Patches for busybox and buildroot)

[Ming-Ching Tiew]

From: "Arkadiusz Patyk" <areq at areq.eu.org>
> 
> I try lzmacat - works.
> but memory usage is disqualification ;(
> 
> 121M    live.tar
> 35M     live.tar.lzma
>  
> ./lzmacat live.tar.lzma > live2.tar
> 
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 13730 areq      25   0  157m 133m 1804 R 99.9  5.2   0:09.79 lzmacat
> 
>

I could make it use less memory but at the expense of
slightly more code and complexity, about slightly more 
than 8 M of memory is all that is needed to decompress 
whatever file size - in user space. And Thomas's ffw distro
does not seem to have anything needing a file bigger than
8M.

As it turns out, I have implemented using this approach,
a kernel patch which allows the lzma-minix ram file system 
to be decompressed using about 128k ram irrespective 
of the file size of the initrd.

Cheers.