libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_extend.c

Index: source/libvpx/vp9/encoder/vp9_extend.c
===================================================================
--- source/libvpx/vp9/encoder/vp9_extend.c	(revision 285372)
+++ source/libvpx/vp9/encoder/vp9_extend.c	(working copy)
@@ -75,18 +75,6 @@
   const int eb_uv = eb_y >> uv_height_subsampling;
   const int er_uv = er_y >> uv_width_subsampling;
 
-#if CONFIG_ALPHA
-  const int et_a = dst->border >> (dst->alpha_height != dst->y_height);
-  const int el_a = dst->border >> (dst->alpha_width != dst->y_width);
-  const int eb_a = et_a + dst->alpha_height - src->alpha_height;
-  const int er_a = el_a + dst->alpha_width - src->alpha_width;
-
-  copy_and_extend_plane(src->alpha_buffer, src->alpha_stride,
-                        dst->alpha_buffer, dst->alpha_stride,
-                        src->alpha_width, src->alpha_height,
-                        et_a, el_a, eb_a, er_a);
-#endif
-
   copy_and_extend_plane(src->y_buffer, src->y_stride,
                         dst->y_buffer, dst->y_stride,
                         src->y_width, src->y_height,