Squashfs: add decompressor entries for lzma and lzo

Add knowledge of lzma/lzo compression formats to the decompressor
framework.  For now these are added as unsupported.  Without
these entries lzma/lzo compressed filesystems will be flagged as
having unknown compression which is undesirable.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

diff --cc fs/squashfs/decompressor.c
Simple merge

diff --cc fs/squashfs/squashfs_fs.h
Simple merge