common/rc: cleanup old .kmemleak files

common/rc: cleanup old .kmemleak files

I've spent a non-negligible amount of time looking into a kmemleak that
didn't exist in the code I was testing because there was an old .kmemleak
file in the results directory.  I don't think this is an intended behaviour,
so I'm proposing to remove these files everytime we capture the result of a
new scan.

Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>