Use "> 0 == false" instead of "== 0"

[PaulRBerg]

> 0 == false is more gas efficient than == 0.

[PaulRBerg]

Update: I'm no longer so confident that > 0 == false is always more gas efficient than == 0. See this.

[PaulRBerg]

Update: if we use --via-ir, it doesn't matter if we are writing >0 == false or == 0.

Locking.

[PaulRBerg]

See related discussion here:

kadenzipfel/gas-optimizations#23