Also in the scope of SWDEV-467540.
Fix sporadic crash in Unit_hipStreamAddCallback_MultipleThreads by
deferring release() of block_command.
The test will invoke 1000 threads on the same stream thus there
is a chance to free block_command too early in original code.
By deferring release() of block_command we can make sure block_command
is always valid during calling block_command->notifyCmdQueue().
Change-Id: I31555ee18e6958e34b89f04181867fa4e932a38c
taosang2
e3ef19e22a