Fixed error concealment when no MBs are decoded in the current pic

Bug: 29493002
Change-Id: I3fae547ddb0616b4e6579580985232bd3d65881e
diff --git a/decoder/ih264d_api.c b/decoder/ih264d_api.c
index e2fa322..431d8db 100644
--- a/decoder/ih264d_api.c
+++ b/decoder/ih264d_api.c
@@ -2136,6 +2136,9 @@
         else
             prev_slice_err = 2;
 
+        if(ps_dec->u4_first_slice_in_pic && (ps_dec->u2_total_mbs_coded == 0))
+            prev_slice_err = 1;
+
         ret1 = ih264d_mark_err_slice_skip(ps_dec, num_mb_skipped, ps_dec->u1_nal_unit_type == IDR_SLICE_NAL, ps_dec->ps_cur_slice->u2_frame_num,
                                    &temp_poc, prev_slice_err);