Fix compiler warning (int vs unsigned)
Fix compiler warning (int vs unsigned)

johnhaddon/OpenShadingLanguage,sjparker/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,brechtvl/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,lgritz/OpenShadingLanguage,sjparker/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,juvenal/OpenShadingLanguage,rlmh/OpenShadingLanguage,sjparker/OpenShadingLanguage,imageworks/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,mcanthony/OpenShadingLanguage,juvenal/OpenShadingLanguage,mcanthony/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,imageworks/OpenShadingLanguage,gzorin/OpenShadingLanguage,gzorin/OpenShadingLanguage,svenstaro/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,gzorin/OpenShadingLanguage,rlmh/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,gzorin/OpenShadingLanguage,gzorin/OpenShadingLanguage,mcanthony/OpenShadingLanguage,brechtvl/OpenShadingLanguage,imageworks/OpenShadingLanguage,svenstaro/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,juvenal/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,Anteru/OpenShadingLanguage,brechtvl/OpenShadingLanguage,aconty/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,svenstaro/OpenShadingLanguage,lgritz/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,mcanthony/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,Anteru/OpenShadingLanguage,juvenal/OpenShadingLanguage,Anteru/OpenShadingLanguage,rlmh/OpenShadingLanguage,lgritz/OpenShadingLanguage,svenstaro/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,aconty/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,rlmh/OpenShadingLanguage,Anteru/OpenShadingLanguage,imageworks/OpenShadingLanguage,sjparker/OpenShadingLanguage,lgritz/OpenShadingLanguage