package/libsndfile: fix CVE-2019-3832

It was discovered the fix for CVE-2018-19758 (libsndfile) was not
complete and still allows a read beyond the limits of a buffer in
wav_write_header() function in wav.c. A local attacker may use this flaw
to make the application crash.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>