test/kv_store_bench.cc: fix resource leak

CID 727984 (#5 of 5): Resource leak (RESOURCE_LEAK)
  leaked_storage: Variable "cb_args" going out of scope leaks the storage
  it points to.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
scratchtool.c: cleanup rados_t on error

Make sure rados_shutdown() get called also in error case.

CID 717106 (#1 of 1): Resource leak (RESOURCE_LEAK)
  leaked_storage: Variable "cl" going out of scope leaks the
  storage it points to.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>