Add basic bits to the cloudabi-toolchain port to support ARMv6.

Though Clang 3.9 and LLD 3.9 will not provide all the necessary bits to
create fully working binaries for ARMv6, start off by putting symlinks
to the tools in place. By the time LLVM trunk fully supports it, I'll
add an option to this port to toggle between 3.9 and trunk.