vp8 rc: Clear system state at the end of calls

Clear system state at the end of rc calls to make sure the state is
consistent before and after

Change-Id: I59fe9c99485b1a8603c20db37961339b7575455f
diff --git a/vp8/vp8_ratectrl_rtc.cc b/vp8/vp8_ratectrl_rtc.cc
index 2098eda..2f23c5b 100644
--- a/vp8/vp8_ratectrl_rtc.cc
+++ b/vp8/vp8_ratectrl_rtc.cc
@@ -168,6 +168,7 @@
   }
 
   vp8_new_framerate(cpi_, cpi_->framerate);
+  vpx_clear_system_state();
 }
 
 void VP8RateControlRTC::ComputeQP(const VP8FrameParamsQpRTC &frame_params) {
@@ -251,6 +252,7 @@
 
   q_ = vp8_regulate_q(cpi_, cpi_->this_frame_target);
   vp8_set_quantizer(cpi_, q_);
+  vpx_clear_system_state();
 }
 
 int VP8RateControlRTC::GetQP() const { return q_; }
@@ -340,5 +342,6 @@
   cpi_->frames_since_key++;
 
   if (cpi_->oxcf.number_of_layers > 1) vp8_save_layer_context(cpi_);
+  vpx_clear_system_state();
 }
 }  // namespace libvpx