aac sbr: align struct member by 32 byte.

Required because it's used in a call to imdct_half(), which is an AVX
function.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/sbr.h

@@ -180,7 +180,7 @@ typedef struct {
     ///Sinusoidal levels
     float              s_m[7][48];
     float              gain[7][48];
-    DECLARE_ALIGNED(16, float, qmf_filter_scratch)[5][64];
+    DECLARE_ALIGNED(32, float, qmf_filter_scratch)[5][64];
     FFTContext         mdct_ana;
     FFTContext         mdct;
     SBRDSPContext      dsp;