compare rust type with llvm value in result, lval_result

[nikomatsakis]

Right now in trans we have this result and lval_result that is the combination of a bcx and a value. It should also include the rust type of this value. This would make it possible to figure out, based solely on result and lval_result, whether something is stored on the stack or not. Right now we have to check if the kind is owned and if the type is immediate.

[catamorphism]

Seems like this is obsolete since trans uses datum now? Closing.