Fix for bug introduced by commit 67c092828d520e95d620f4c5a5a5cc90fdbd0466
Merge pull request #72 from couteau/master

Fix detection of eventfd
fix delete query for removing files if a spotify playlist is deleted
Merge pull request #74 from chme/spotify

fix delete query for removing files if a spotify playlist is deleted
improve selects for files table by removing the join to the groups table
db update v16 and cache update v2
Improve selects for files table by removing the (f.album <> '' AND
f.album IS NOT NULL) from the where clause for album and artist. These
are unnecessary because forked-daapd makes sure that an artist or album
name exists.
Improve select for files table by removing f.media_kind = 32 from the
queries (forked_daapd has no media_kind = 32).
Optimize the indexes on the files table to speed up select queries
optimize queries and indexes for composer/genre