sd-event: store and compare per-module static origin id

sd-event: store and compare per-module static origin id

sd-event objects use hashmaps, which use module-global state, so it is not safe
to pass a sd-event object created by a module instance to another module instance
(e.g.: when two libraries static linking sd-event are pulled in a single process).
Initialize a random per-module origin id and store it in the object, and compare
it when entering a public API, and error out if they don't match, together with
the PID.