Update Fuse (the Spectrum emulator) ports to their latest versions.

emulators/fuse -> 1.6.0

• add ALSA, OSS (was implicit default), PulseAudio options for sound
• prefer GTK 3 over GTK 2, push down cairo dependency
• prefer SDL 2 over SDL 1

emulators/libspectrum -> 1.5.0 (needed for fuse)
emulators/fuse-utils: no update, but force rebuild against new libspectrum

Reported by: upstream mail