add --disable-sndfile to avoid build failure

- build fails on non-ancient OSX platforms if libsndfile is present
- low risk for all platforms as scope is limited to libsamplerate/examples/


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5252 b64f7644-9d1e-0410-96f1-a4d463321fa5