LzmaTools: don't self assign values

It seems the code tries to trick the compiler the argument
is actually used. However compilers became too smart to
fool them so easily an now warn. Gcc and clang don't seem
to emit a warning when the argument is unused. If so it
should be decorated with unused / (void).

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>