Fix the RUSTUP_UPDATE_ROOT value in rustup-setup.sh
Fix the RUSTUP_UPDATE_ROOT value in rustup-setup.sh

From multirust-rs-binaries to static.rust-lang.org.

Also use rustup-setup instead of multirust-setup.

inejge/rustup.rs,polonez/rustup.rs,inejge/rustup.rs,nodakai/rustup.rs,theindigamer/rustup.rs,Boddlnagg/rustup.rs,theindigamer/rustup.rs,nodakai/rustup.rs,inejge/rustup.rs,nodakai/rustup.rs,polonez/rustup.rs,nodakai/rustup.rs,theindigamer/rustup.rs,polonez/rustup.rs,rust-lang/rustup,theindigamer/rustup.rs,Boddlnagg/rustup.rs,rust-lang/rustup,inejge/rustup.rs,rust-lang/rustup,theindigamer/rustup.rs,rust-lang/rustup,Boddlnagg/rustup.rs,inejge/rustup.rs,nodakai/rustup.rs,polonez/rustup.rs,Boddlnagg/rustup.rs,rust-lang/rustup,Boddlnagg/rustup.rs,polonez/rustup.rs