[DLM] Don't segfault if lvbptr is NULL
[DLM] Don't segfault if lvbptr is NULL

Calling dlm_lock* with  LKF_VALBLK and sb_lvbptr set
to NULL could cause libdlm to segfault.

Now it returns -1/EINVAL

Signed-off-by: Christine Caulfield <992cedbe1eac7dbaff482fcb880a50b57e6b8062@redhat.com>

stevenraspudic/resource-agents,stevenraspudic/resource-agents,asp24/resource-agents,asp24/resource-agents,asp24/resource-agents,stevenraspudic/resource-agents