When the 'delete' flag is set, the file was removed from the index and
the item was removed from the pending file queue (m_cache). When a
'created' event arrives before the queue has been processed, the flag
was merged into the queue item, but never processed (delete + create),
i.e. the file was omitted from the index.
In case a created/modified file was moved to the m_pendingFiles queue
(files to be reindexed later) and deleted, the pending files timer may
fire before process is run, and the indexNewFile/indexModifiedFile
signal is emitted for a no longer existing file. Although this is handled
in the indexer, this causes unnecessary work.
Emit the removeFileIndex immediately and remove the file from all
queues.
A deleted file/folder is kept in the m_recentlyEmitted list, to avoid
excessive events when e.g. a temporary file is created/deleted in short
period of time.