Clean up some no-longer-used parameters

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Remove per-worker stats stuff

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Add per-thread initialize/finalizer and data

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>