[SCons] Use more generic flag for warning suppression
[SCons] Use more generic flag for warning suppression

Older versions of Clang don't support '-Wno-unused-result'.

Heathckliff/cantera,imitrichev/cantera,imitrichev/cantera,Heathckliff/cantera,Heathckliff/cantera,Heathckliff/cantera,imitrichev/cantera,imitrichev/cantera,imitrichev/cantera,Heathckliff/cantera,Heathckliff/cantera,imitrichev/cantera