Add _STDC_CONSTANT_MACROS for FFmpeg(2.8.1) plugin
Add _STDC_CONSTANT_MACROS for FFmpeg(2.8.1) plugin

micler/oiio,bdeluca/oiio,OpenImageIO/oiio,YangYangTL/oiio,OpenImageIO/oiio,YangYangTL/oiio,OpenImageIO/oiio,lgritz/oiio,bdeluca/oiio,OpenImageIO/oiio,bdeluca/oiio,lgritz/oiio,micler/oiio,YangYangTL/oiio,YangYangTL/oiio,micler/oiio,bdeluca/oiio,lgritz/oiio,lgritz/oiio,micler/oiio