buildroot

flite: depend on alsa-lib when available

The flite configure script detects the availability of alsa-lib. Add alsa-lib
to flite dependencies to make sure alsa-lib is always detected when
available.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>