hwc3: do not check weak reference for client alive

Client weak ref is expired before the client destructor is called.

A new client could be created in between and its weak ref gets reset
unexpectedly during the prior client destruction.

Use a bool variable to indicate if the client is alive.

Bug: 215414703
Change-Id: I221f613cf8af81e1a79631ba28b1a99e6c63eb3a
2 files changed