[Linux]: Add support for Linux aarch64. (#4225)

Author: xuelongqy

tools/install-rust-dependencies

@@ -11,7 +11,7 @@ rustup toolchain install $NIGHTLY-aarch64-apple-darwin --force-non-host
 rustup component add rust-src --toolchain $NIGHTLY-aarch64-apple-darwin
 rustup component add rust-src --toolchain $NIGHTLY-x86_64-apple-darwin
 if [[ `uname` == "Linux" ]]; then
-  rustup component add rust-src --toolchain $NIGHTLY-x86_64-unknown-linux-gnu
+  rustup component add rust-src --toolchain $NIGHTLY-$(uname -m)-unknown-linux-gnu
 fi
 
 # Android