Fix crashes with fwd-kf and keyframe filtering

Change-Id: Iae8d319bc62a3fa7595d598dcde68aff3c33039c

av1/encoder/encode_strategy.c

diff --git a/av1/encoder/encode_strategy.c b/av1/encoder/encode_strategy.c
index e3c869a..de3c565 100644
--- a/av1/encoder/encode_strategy.c
+++ b/av1/encoder/encode_strategy.c
@@ -931,6 +931,7 @@
   }
   const int apply_filtering =
       oxcf->pass == 2 && frame_params->frame_type == KEY_FRAME &&
+      frame_params->show_frame &&
       cpi->rc.frames_to_key > NUM_KEY_FRAME_DENOISING && noise_level > 0 &&
       !is_lossless_requested(oxcf) && oxcf->arnr_max_frames > 0;
   // Save the pointer to the original source image.

av1/encoder/temporal_filter.c

diff --git a/av1/encoder/temporal_filter.c b/av1/encoder/temporal_filter.c
index 2307996..556bb5a 100644
--- a/av1/encoder/temporal_filter.c
+++ b/av1/encoder/temporal_filter.c
@@ -1573,12 +1573,11 @@
                        &sigma, &frames_to_blur_backward,
                        &frames_to_blur_forward);
     start_frame = distance + frames_to_blur_forward;
+    cpi->common.showable_frame =
+        (strength == 0 && frames_to_blur == 1) ||
+        (cpi->oxcf.enable_overlay == 0 || cpi->sf.disable_overlay_frames);
   }
 
-  cpi->common.showable_frame =
-      (strength == 0 && frames_to_blur == 1) ||
-      (cpi->oxcf.enable_overlay == 0 || cpi->sf.disable_overlay_frames);
-
   // Setup frame pointers, NULL indicates frame not included in filter.
   for (frame = 0; frame < frames_to_blur; ++frame) {
     const int which_buffer = start_frame - frame;