Skip unnecessary search of identical frames

vp8_get_compressed_data() was defeating logic in
encode_frame_to_datarate() that determined the reference buffers to
search and forcing all frames to be eligible to search. In cases
where buffers have identical contents, this is unnecessary extra
work.

Change-Id: I9e667ac39128ae32dc455a3db4c62e3efce6f114

vp8/encoder/onyx_if.c

diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index d9ff6b0..99a09de 100644
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -5209,8 +5209,6 @@
     {
 
         // return to normal state
-        cpi->ref_frame_flags = VP8_ALT_FLAG | VP8_GOLD_FLAG | VP8_LAST_FLAG;
-
         cm->refresh_entropy_probs = 1;
         cm->refresh_alt_ref_frame = 0;
         cm->refresh_golden_frame = 0;