Samples buffer ref is allocated and loaded with the uninitialized data
pointers:
av_asrc_buffer_add_buffer()
-> av_asrc_buffer_add_samples()
-> avfilter_get_audio_buffer_ref_from_arrays(data, ...)
...which leads to a crash with at least lavfi/ashowinfo in case of !NULL
(see the for loop while samplesref->data[plane]).
The function strtok_r() is part of the POSIX.1 specification, but is not
available on some platforms. We provide an internal implementation, so we
do not need to rely on a platform implementation.
Fix GCC warning:
asrc_abuffer.c: In function ‘init’:
asrc_abuffer.c:258: warning: passing argument 1 of ‘strtok_r’ discards qualifiers from pointer target type