Move lvl <= $crate::max_level() inside called functions

[EFanZh]

This change will reduce binary size at the cost of some performance loss.

[EFanZh]

I noticed a project I am working on has a decent amount of size increase after upgrading the log dependency, it was cause by #446, which I am not able to workaround, so I was looking for other ways to reduce the binary size impact, and this is what I came up with.

If the performance loss is unacceptable, how about using an optional feature to provide this binary-size-over-performance behavior?

[EFanZh]

Close as this will expand argument too early, causing behavior change.

[Thomasdezeeuw]

@EFanZh have you tried the log crate's filter features (https://docs.rs/log/latest/log/#compile-time-filters)? Those will help remove trace, debug (and more if desired) from the binary. It's also (part of) the reason why the if statement if outside of the function.

[EFanZh]

@Thomasdezeeuw Most of my logs are required to be printed out, so disabling logs is not an option.