Add -Winit-self to warnings

This is very handy :)

Change-Id: I44c0c8d42f8dc6b652d9784cbbe91d4c9f45d472
Reviewed-on: http://review.couchbase.org/28073
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>