Considering the process can be terminated in the cases like ctrl+c,
kill command or memory fault, the ref is tracked in the per process
structure spdk_nvme_controller_process and whenever there is other
process attaches or detaches the controller, a scan will be issued
to cleanup those unexpectedly exited processes.
Change-Id: Ib4f974f567a865748d42da4ead49edd383dfc752
Signed-off-by: GangCao <gang.cao@intel.com>
ec5b6fed61