sfdisk: add deprecated --Linux

sfdisk: add deprecated --Linux

The sfdisk does not care about compatibility with classic DOS
partitioning, and it does not warn about incompatibility with DOS at
all. It means that --Linux is default and it's unnecessary to use
this option.

It's the same situation like with "--unit S", these options are very
probably often used in scripts, and these all is default now. So for
backward compatibility new sfdisk accepts these options on command
line, but prints "option is deprecated" warning message.

Signed-off-by: Karel Zak <kzak@redhat.com>