[shmem5] corrected typo for generation-id
[shmem5] fixed typo for generation-id
[shmem5] extended SegmentInfo to store the datasrc gen ID. added getter too.
[shmem5] updated memmgr so it includes datasrc genID in segment info updates
[shmem5] use gen ID in memmgr's handling of sgmt info update ack.
[shmem5] use generation ID for zone_update command in memmgr.
[shmem5] refactor memmgr: separate current/old data src info.

on second thought, it seems sufficient to only work on the current data src
info for the case of data source reconfiguration.
[shmem5] make sure failure of initial datasrc config terminates memmgr

this simplifies the main cases as we can assume there's at least one generation
of data sources.
[shmem5] send 'cancel' cmd for old datasrc to builder on datasrc reconfig.
[shmem5] supported cancel command in memory segment builder.
[shmem5] refactor: change _old_datasrc_info to a dict, not set.

this seems to be convenient for expected usage later.
[shmem5] cleanup and small fix: just ignore mismatch genID for update ack.

that's possible depending on the timing.  helper function isn't needed anymore
so removed.
[shmem5] updated libmemmgr to cancel datasrcs and remove mapped files.

this is a necessary cleanup on migrating a generation of data sources to
another.
[shmem5] update memmgr to handle cancel-completed from the builder.
[shmem5] update memmgr to handle release segments ack and unsubscribed reader

this should complete the memmgr side of data source reconfiguration.
[shmem5/m] corrected log placeholder
[shmem5] revised DataSrcClientsMgr::reconfigure() to accept whole config

not just "classes", but also "_generation_id".  (the latter is not yet used
for now).
[shmem5] don't apply new generation of data sources if there's waiting sgmt.

we'll store them in a placeholder structure until all segments are ready
(not done in this commit).  also retrieve the gen ID from the passed config.
[shmem5] make sure sgmt info update to the pending data if genid matches.

and also perform swap if the pending data are ready as a result of the update.
[shmem5] make sure generation-id exists in segmentInfoUpdate()

also corrected typo in the builder side.