swr: add native matrix for SIMD

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/rematrix.c

@@ -346,6 +346,7 @@ int swri_rematrix_init(SwrContext *s){
 void swri_rematrix_free(SwrContext *s){
     av_freep(&s->native_matrix);
     av_freep(&s->native_one);
+    av_freep(&s->native_simd_matrix);
 }
 
 int swri_rematrix(SwrContext *s, AudioData *out, AudioData *in, int len, int mustcopy){

libswresample/swresample_internal.h

@@ -95,6 +95,7 @@ struct SwrContext {
     float matrix[SWR_CH_MAX][SWR_CH_MAX];           ///< floating point rematrixing coefficients
     uint8_t *native_matrix;
     uint8_t *native_one;
+    uint8_t *native_simd_matrix;
     int32_t matrix32[SWR_CH_MAX][SWR_CH_MAX];       ///< 17.15 fixed point rematrixing coefficients
     uint8_t matrix_ch[SWR_CH_MAX][SWR_CH_MAX+1];    ///< Lists of input channels per output channel that have non zero rematrixing coefficients
     mix_1_1_func_type *mix_1_1_f;