Fixed initialization of frame buffer ref counters

Only the first frame buffer ref counter was being initialized
because the index was fixed at 0 rather than using i.

Change-Id: Ib842298be4a5e3607f9e21c2cd4bfbee4054ffc4

vp8/common/alloccommon.c

diff --git a/vp8/common/alloccommon.c b/vp8/common/alloccommon.c
index 216590c..376707e 100644
--- a/vp8/common/alloccommon.c
+++ b/vp8/common/alloccommon.c
@@ -70,7 +70,7 @@
 
     for (i = 0; i < NUM_YV12_BUFFERS; i++)
     {
-        oci->fb_idx_ref_cnt[0] = 0;
+        oci->fb_idx_ref_cnt[i] = 0;
         oci->yv12_fb[i].flags = 0;
         if (vp8_yv12_alloc_frame_buffer(&oci->yv12_fb[i], width, height, VP8BORDERINPIXELS) < 0)
         {