riotbuild/Dockerfile: remove unused MIPS toolchain, remove old MSP430 toolchain#263

crasbe wants to merge 3 commits intoRIOT-OS:masterRIOT-OS/riotdocker:masterfrom

crasbe:pr/remove_mips_toolchaincrasbe/riotdocker:pr/remove_mips_toolchainCopy head branch name to clipboard