Add the 7zr command line tool, which is a version of the 7z application
that only supports 7z archives.
7z is one of the two compression formats supported in H3C firmware
images (the alternative would be ARJ).
(Alternatively, the 7zr command line tool could also be built from a
current version of the public-domain LZMA SDK. That would require
repackaging the source package, as it is only provided in 7z format.)
Signed-off-by: Jan Hoffmann <jan@3e8.eu>
