kr_module_load(): don't pass the_engine in module->data

kr_module_load(): don't pass the_engine in module->data

It was a confusing way of repurposing the field.

My comment from over five years ago (129002fc0d) said that
some external C modules might be relying on this.
But that certainly sounds moot nowadays.  To get more confidence,
I rechecked all kr_module::data references (as found by libclang).