[vector] RFR (M): Ensure intrinsics are parameterized with non-capturing lambdas

[Brian Goetz]

> That would be nice.  In the end I'd like to be able to say
> things like, "this apply method requires a state-free
> crackable lambda", and have it checked by javac.

Stateless and crackable are slightly different from each other.  

Crackable (like Serializable) is asking to bake in _extra_ goop when converting a block of code to a lambda. We handle serializability via target typing; if the target type includes Serializable, we ask the metafactory to generate extra runtime goop.  Crackability would be in the same category, and could similarly be handled by a marker interface which could be mixed into the target type.  (This is how you ask for expression trees in C#, too.)  

Statelessness is kind of the opposite, because you’re asking for a _restricted_ subset of lambda behavior.  A This seems more of a tooling request (like @Override), where you’re including an assertion in the code, and you’re asking the tools to help you spot violations of the assertion.  

But, neither is all that hard.