thread.h: add atomic_exchange for int and long long
thread.h: add atomic_exchange for int and long long

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