Cleanup toolchain files, add clang versions
arx: Add builds for different Clang versions
innoextract: Add builds for diff. clang versions
Also add Clang 2.8 toolchain & builds
Remove Clang 2.8 and 2.9 builds for now

They don't play nice with the installed libstdc++ and don't know the
-stdlib option.
Use scm build of clang for clang-analyzer runs
arx: Disable ekopath builds

They are broken and just waste a time. Will try again for future
Ekopath releases.