sdl_mixer: Enabled optional FluidSynth support
opendingux: GCW0: defconfig: Enabled kmod tools

This is useful for testing drivers. Also it will be needed once we get
USB OTG running, so we can load drivers for USB devices when they are
plugged.
opendingux: GCW0: defconfig: Enabled boost (C++ lib)

Enabled all components that someone might conceivably want to use on
a handheld console.