--ghc-strict-data and --ghc-strict

[nad]

I've implemented two flags that make the GHC backend emit possibly more strict code:

• --ghc-strict-data: Based on the GHC language extension StrictData. Makes most inductive constructors strict.
• --ghc-strict: Based on the GHC language extension Strict. Makes the code mostly strict.

Are there any thoughts about this before I push the changes?

I'm not sure how useful these flags are:

• They are activated for the entire program (backend options cannot be used in OPTIONS pragmas, and furthermore the translation to tree-less syntax depends on the evaluation strategy).
• There is no way to specify that a particular constructor or function should be lazy.
• If the goal is to create strict code, then perhaps one should target a different language.

However, I wanted to be able to test that --erased-cubical works correctly in a strict, functional setting.