avcodec/ac3_tab: Zero-terminate ff_ac3_sample_rate_tab

This is required to use it as an AVCodec.supported_samplerates array.
Adding the sentinel has been forgotten in 4679a474.
Without it e.g. the FATE-test ffmpeg-filter_complex_audio fails with ASAN.
Reviewed-by: Carl Eugen Hoyos <ceffmpeg@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/ac3tab.c

@@ -126,7 +126,7 @@ const uint8_t ff_ac3_dec_channel_map[8][2][6] = {
 };
 
 /* possible frequencies */
-const int ff_ac3_sample_rate_tab[3] = { 48000, 44100, 32000 };
+const int ff_ac3_sample_rate_tab[] = { 48000, 44100, 32000, 0 };
 
 /* possible bitrates */
 const uint16_t ff_ac3_bitrate_tab[19] = {

libavcodec/ac3tab.h

@@ -33,7 +33,7 @@ extern const uint8_t  ff_ac3_channels_tab[8];
 extern av_export_avcodec const uint16_t avpriv_ac3_channel_layout_tab[8];
 extern const uint8_t  ff_ac3_enc_channel_map[8][2][6];
 extern const uint8_t  ff_ac3_dec_channel_map[8][2][6];
-extern const int      ff_ac3_sample_rate_tab[3];
+extern const int      ff_ac3_sample_rate_tab[];
 extern const uint16_t ff_ac3_bitrate_tab[19];
 extern const uint8_t  ff_ac3_rematrix_band_tab[5];
 extern const uint8_t  ff_eac3_default_cpl_band_struct[18];