Fix sgx install

Author: jack-fortanix

ct.sh

@@ -24,7 +24,7 @@ elif [ $TOOLCHAIN = "coreio_nightly" ]; then
 
 elif [ $TOOLCHAIN = "sgx" ]; then
 
-    rustup toolchain add $SGX_NIGHTLY
+    rustup target add --toolchain $SGX_NIGHTLY x86_64-fortanix-unknown-sgx
     cargo +$SGX_NIGHTLY test --no-run --target=x86_64-fortanix-unknown-sgx --features=sgx --no-default-features
 
 fi