Remove unused variable vp9_64x64_zeros

Remove the unused variable vp9_64x64_zeros from vp9_encodeframe_.

Change-Id: I34bfdcab9a9105440ad05154c1e0516e70258785

vp9/encoder/vp9_encodeframe.c

diff --git a/vp9/encoder/vp9_encodeframe.c b/vp9/encoder/vp9_encodeframe.c
index b74609b..15c3f56 100644
--- a/vp9/encoder/vp9_encodeframe.c
+++ b/vp9/encoder/vp9_encodeframe.c
@@ -123,7 +123,6 @@
 static unsigned int alt_activity_measure(MACROBLOCK *x, int use_dc_pred) {
   return vp9_encode_intra(x, use_dc_pred);
 }
-DECLARE_ALIGNED(16, static const uint8_t, vp9_64x64_zeros[64*64]) = {0};
 
 // Measure the activity of the current macroblock
 // What we measure here is TBD so abstracted to this function