shadowsocks-rust is shadowsocks written in rust, with high performance
for AES AEAD ciphers (while much lower for non-ones).
However with the lack of rust toolchain, by now we can only download
pre-compiled binaries for quick setup and this Makefile needs to be
rewritten when rust toolchain is up.
Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>