OIIO: added support for OIIO 1.x

OIIO 2.x uses std::unique_ptr while 1.x uses raw pointers. Olive can now handle
both, manually destroying the raw pointers when necessary if running on OIIO
1.x.

app/codec/oiio/oiiodecoder.cpp

@@ -139,6 +139,9 @@ void OIIODecoder::Close()
 {
   if (image_ != nullptr) {
     image_->close();
+#if OIIO_VERSION < 10903
+    OIIO::ImageInput::destroy(image_);
+#endif
     image_ = nullptr;
   }