Sometimes, playback needs to be fully uninitialized and reinitialized
without "officially" closing and reopening the playlist entry. This
happens with PT_RELOAD_FILE, which is triggered by edition switching and
also DVD/BD title switching. (Not really sure why it goes through so
much pain for such obscure cases. All it gains is not resetting "local"
options, and not signaling a reload to the client API. Whatever.)
The recent filter change freed filter_root too early without recreating
it, so it crashed on edition switching.
Fixes#5587.