Adding new gcc warnings

[Julien ÉLIE]

Responding to myself:

> -Wlogical-op led to unclear code when fixed (according to the other mail
> you wrote about INN; unless I misunderstood your meaning?)

I read too fast.  You clearly said "it's worth fixing code that triggers 
-Wlogical-op because it's often unclear", so this warning should be used.

-- 
Julien ÉLIE

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