problem building depot for fb_sdl

[Duss Pirmin]

Hello all

I have two clones of Genode (18.02-20-g1f7b5e75b) on two different machines.

On my Ubuntu Artful fb_sdl can't be built due to a missing header file  
(SDL/SDL.h). I then tested it on my ARCH Linux, where the build works  
flawless.

Does the recipe for fb_sdl by accident use some header files from the  
build system? Can this cause any problems or should I just install the  
missing header files on my Ubunt?

Best regards,

Pirmin