libsoxr: new package

Building tests fails mainly because of the cross-compilation, so they
are disabled for the moment.

Signed-off-by: Hadrien Boutteville <hadrien.boutteville@gmail.com>
Reviewed-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>