Increase filter buffer size to silence warnings

The asan reports global-buffer-overflow on address of the
filter coefficient buffer.

BUG=b/324147074

Change-Id: Idf6db1394f2df26e6802f13073d34cd97a7ce8dc
(cherry picked from commit b53a6307466418464605c858a5f5e2347ce805b0)

av1/encoder/tune_vmaf.c

diff --git a/av1/encoder/tune_vmaf.c b/av1/encoder/tune_vmaf.c
index 91db3db..847571f 100644
--- a/av1/encoder/tune_vmaf.c
+++ b/av1/encoder/tune_vmaf.c
@@ -247,7 +247,7 @@
 
 // 8-tap Gaussian convolution filter with sigma = 1.0, sums to 128,
 // all co-efficients must be even.
-DECLARE_ALIGNED(16, static const int16_t, gauss_filter[8]) = { 0,  8, 30, 52,
+DECLARE_ALIGNED(16, static const int16_t, gauss_filter[9]) = { 0,  8, 30, 52,
                                                                30, 8, 0,  0 };
 static AOM_INLINE void gaussian_blur(const int bit_depth,
                                      const YV12_BUFFER_CONFIG *source,