package/pulseaudio: use the new fftw-single package

This patch add an explicitly dependency to fftw-single (the only compatible
fftw's flavor) instead of default behavior where the package do assumption
about the compatible version.

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>