[Clam-devel] Changing to fftw3

[Pau Arumi]

In order to proceed in the fftw -> fftw3, and after David
assessed that their numbers where equivalents (but fftw3 much
fastest), I'd like to change the defaults build options to:
with_fftw = no
with_fftw3 = yes
Which is the reverse from how it's now.

The user migration will be:
- install the fftw3-dev if needed
- run scons configure

Do I proceed?
I'll interpret 24h silence as a yes.

Pau