tvix/eval: arithmetic builtins don't handle thunks at all

#197
Opened by sterni at 2022-09-19T10·28+00

E.g.:

tvix-repl> builtins.add (builtins.add 3 2) 3
ThunkForce(Error { kind: TypeError { expected: "number (either int or float)", actual: "int" }, span: Span { low: Pos(1), high: Pos(34) } })

This is because we reuse the arithmetic_op! macro from the VM which doesn't need to care about thunks because OpForce is emitted before and the unwrapped value pushed onto the stack.