Fix GF interval for non-lagged ARFs

When ARFs are enabled in non-lagged compress modes, the GF interval
was being reset to zero. Non-lagged ARF updates were enabled in commit
63ccfbd, but this incorrect GF interval caused a quality regression.

Change-Id: I615c3b493f4ce2127044f4e68d0bcb07d6b730c3

vp8/encoder/firstpass.c

@@ -1403,6 +1403,7 @@ static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
 
     // Should we use the alternate refernce frame
     if (cpi->oxcf.play_alternate &&
+        cpi->oxcf.lag_in_frames &&
         (i >= MIN_GF_INTERVAL) &&
         (i <= (cpi->frames_to_key - MIN_GF_INTERVAL)) &&          // dont use ARF very near next kf
         (((next_frame.pcnt_inter > 0.75) &&

vp8/encoder/onyx_if.c

@@ -1344,8 +1344,8 @@ void vp8_new_frame_rate(VP8_COMP *cpi, double framerate)
         cpi->max_gf_interval = 12;
 
 
-    // Special conditions when altr ref frame enabled
+    // Special conditions when altr ref frame enabled in lagged compress mode
-    if (cpi->oxcf.play_alternate)
+    if (cpi->oxcf.play_alternate && cpi->oxcf.lag_in_frames)
     {
         if (cpi->max_gf_interval > cpi->oxcf.lag_in_frames - 1)
             cpi->max_gf_interval = cpi->oxcf.lag_in_frames - 1;