rdist01: fix mistakes

Fix the following mistakes in the script:
1) the way it gets dirname and basename of files is broken
2) ${FILES} and ${HOSTS} get substituted when generating distfile
3) the way it calculates sum of files on RHOST is broken
4) there is no $DIRECTORIES variable

Signed-off-by: Simon Xu <xu.simon@oracle.com>
mc_cmds: Multicast ping being disabled should not fail the test

Signed-off-by: Simon Xu <xu.simon@oracle.com>