package/octave: add optional libsndfile support
GNU Octave supports the --with-sndfile configure option since v4.0.0.
For reference, commit 40ea68b4b2 "package/octave: new package"
introduced the package at v7.1.0.
This commits adds this optional support.
Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>