Hm, sorry about flip-flopping on this issue, but now that I actually read this in words it seems more awful then when I imagined this in my head. 

That being said, I like only having one `log_enabled!` macro, and I think that we can just rely on LLVM optimizations to figure this out. The macro can be defined as:

```rust
macro_rules! log_enabled( ($lvl:expr) => (
  $lvl <= _log_level() && (log != 4 || cfg(not(ndebug)))
) )
```

Or at least I think I got the boolean logic there right