Travis: do test builds with AVX2 and AVX512 (can't test, but can check build)
Travis: do test builds with AVX2 and AVX512 (can't test, but can check build)

OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio