[seL4] run_tests needs mlton-compiler gcc-arm-none-eabi

On Ubuntu 14.04, after attempting to follow the instructions, I found I needed to add two extra packages. I needed mlton-complier for CParserTools and gcc-arm-none-eabi for CBaseRefine. gcc-arm-linux-gnueabi is a documented dependency for 14.04 and was already installed when the CBaseRefine test was failing. After installing those two packages and the documented latex extras all 31 regression tests passed.