Fix for metadata in Keyframes

In the case of Keyframes that are temporally filtered, the metadata
currently being written to bitstream is incorrect.
This patch fixes the issue.

Change-Id: I32d88278b063100d74d1429ab2d16db919133f98

av1/encoder/encode_strategy.c

diff --git a/av1/encoder/encode_strategy.c b/av1/encoder/encode_strategy.c
index 1e99cec..66e2a7c 100644
--- a/av1/encoder/encode_strategy.c
+++ b/av1/encoder/encode_strategy.c
@@ -967,6 +967,10 @@
     aom_extend_frame_borders(&cpi->alt_ref_buffer, num_planes);
     // Use the filtered frame for encoding.
     frame_input->source = &cpi->alt_ref_buffer;
+    // Copy metadata info to alt-ref buffer.
+    aom_remove_metadata_from_frame_buffer(frame_input->source);
+    aom_copy_metadata_to_frame_buffer(frame_input->source,
+                                      source_kf_buffer->metadata);
     *temporal_filtered = 1;
   }