[seL4] Building seL4x86_64 on Debian

I thought I got all of the host dependencies installed, but evidently I am doing something wrong. I am building on Debian 9 (x86_64) system. I ran the init script from the build directory with the -DPLATFORM=x86_64 and -DSIMULATION=0 options. I then ran ninja with no options. Please find attached the output of running these 2 steps. I'd appreciate a gentle nudge in the right direction.

Thanks!

Dave