vgsp-sema: only a real session end may request the discovery flush (ISSUE-0002)

A redundant channel delete (a FREE for a handle that never registered, or
a repeated delete after the session already ended) found the channel set
empty while the next client was already starting and re-armed the flush,
which then executed mid-startup and wiped that client's discovery state
(and dropped its pending releases): the client spun at its first channel.
Track whether a session's channel has registered since the last flush and
request the flush only on the true existed->empty transition; redundant
deletes are inert.

0 files changed, 0 insertions, 0 deletions