distro/tiny: Allow commercial packages (for MP3 playback)

To use your board as MP3 player, you'll need some libs with non-standard
licensing.
fpga-image: Fail compile when "fpga.bin" hasn't been generated

Xilinx tools don't return error codes, so you cannot tell if they fail.

Assume that when no fpga.bin was generated by the script, that the
compile must have failed.