GCC 4.8 warning fix.
GCC 4.8 warning fix.

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