It is only called in one place, where from_server is already set to the same as the argument.
Rename rebuild_all_ison() to rebuild_notify_ison_all().
Make rebuild_notify_ison() and rebuild_notify_ison_all() static, they are only called from
this file.
This change means that struct.h no longer needs to include alist.h, so it will be indirectly included in a lot
fewer other files.
As a consequence, server.h needs to include notify.h to get the definitions of those data types.
