aggregateChanges: Remove the callback agrument
aggregateChanges: Remove the callback agrument

This makes the code slightly easier to follow and test. Plus having
less arguments is usually better too.

Note that the only caller (accumulateChanges) already checks that
paths is not empty.

syncthing/syncthing-inotify,imsodin/syncthing-inotify,imsodin/syncthing-inotify,plouj/syncthing-inotify,syncthing/syncthing-inotify,plouj/syncthing-inotify,syncthing/syncthing-inotify,imsodin/syncthing-inotify,plouj/syncthing-inotify