Fix gcc compiler warnings
Fix gcc compiler warnings

mcanthony/oiio,YangYangTL/oiio,scott-wilson/oiio,bdeluca/oiio,sambler/oiio,mcanthony/oiio,cwilling/oiio,micler/oiio,scott-wilson/oiio,scott-wilson/oiio,scott-wilson/oiio,OpenImageIO/oiio,OpenImageIO/oiio,YangYangTL/oiio,lgritz/oiio,YangYangTL/oiio,mcanthony/oiio,micler/oiio,cwilling/oiio,bdeluca/oiio,lgritz/oiio,mcanthony/oiio,micler/oiio,sambler/oiio,cwilling/oiio,micler/oiio,bdeluca/oiio,cwilling/oiio,YangYangTL/oiio,lgritz/oiio,OpenImageIO/oiio,sambler/oiio,lgritz/oiio,sambler/oiio,bdeluca/oiio,OpenImageIO/oiio