avcodec/alsdec: Clear MPEG4AudioConfig so that no use of uninitialized memory is possible

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 6e6bd548

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

libavcodec/alsdec.c

@@ -284,7 +284,7 @@ static av_cold int read_specific_config(ALSDecContext *ctx)
     GetBitContext gb;
     uint64_t ht_size;
     int i, config_offset;
-    MPEG4AudioConfig m4ac;
+    MPEG4AudioConfig m4ac = {0};
     ALSSpecificConfig *sconf = &ctx->sconf;
     AVCodecContext *avctx    = ctx->avctx;
     uint32_t als_id, header_size, trailer_size;