rbd: switch strtok to strtok_r
rbd: switch strtok to strtok_r

The strtok is not thread safe, there could be several threads will
call the tcmu_rbd_open() at the same time.

And sometimes we can randomly hit some errors like:

[ERROR] tcmu_rbd_open:877 datapool/block0: Could not get image name

But when try it again it will succeed.

Signed-off-by: Xiubo Li <d6cd9ec469dfb11098caa077ea0b7b3220fc70dc@redhat.com>

open-iscsi/tcmu-runner,open-iscsi/tcmu-runner