Fix Coverity CID 38598
Fix Coverity CID 38598

Commented out the (seemingly unused and dead) parts that responsible for
derivative.

JonWel/CoolProp,dcprojects/CoolProp,CoolProp/CoolProp,DANA-Laboratory/CoolProp,CoolProp/CoolProp,JonWel/CoolProp,JonWel/CoolProp,henningjp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,DANA-Laboratory/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,DANA-Laboratory/CoolProp,dcprojects/CoolProp,CoolProp/CoolProp,dcprojects/CoolProp,DANA-Laboratory/CoolProp,JonWel/CoolProp,DANA-Laboratory/CoolProp,JonWel/CoolProp,henningjp/CoolProp,JonWel/CoolProp,JonWel/CoolProp,DANA-Laboratory/CoolProp,henningjp/CoolProp,dcprojects/CoolProp,dcprojects/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,dcprojects/CoolProp,henningjp/CoolProp,dcprojects/CoolProp,henningjp/CoolProp,DANA-Laboratory/CoolProp