Rust 1.49.0

You can use this tarball for the next major release of Rust (1.50.0), if a newer Rust 1.49 hasn't been released.

To use them, do the following.

$ mkdir -p /path/to/rust-1.50.0/build/cache/2020-12-31/
$ cp *.tar.xz /path/to/rust-1.50.0/build/cache/2020-12-31/