Auto merge of #125579 - Noratrieb:print-host, r=davidtwco

Add `--print host-tuple` to print host target tuple

People often parse `-vV` output to get to the host tuple, which is annoying to do. It's easier to just get it directly.

I called it "host-tuple" instead of "host" because it's clearer that it's just the target name. I'm open to different names, but I think this one is fine.

a quick GitHub search for `'^host` reveals many instances of people doing the parsing, for example:

https://github.com/japaric/xargo/blob/68e0ca57cd90837fe02f262f074182f9cfeb6227/README.md?plain=1#L369
https://github.com/taiki-e/setup-cross-toolchain-action/blob/0e38473b0c562d6db19a98d3ec20a80f7ac189ae/main.sh#L96
https://github.com/taiki-e/cargo-llvm-cov/blob/8a3553b86551eabf9c30c060b1f72a5bbccb98c6/README.md?plain=1#L625
https://github.com/SiliconLabs/cpc-nvm3/blob/43f3ec39709b30700ef7f39d91fa647974323bf1/do.sh#L35

needs a compiler FCP. I could also do an MCP but I think just an FCP here makes the most sense.

Author: bors

src/machine.rs

@@ -691,7 +691,7 @@ impl<'tcx> MiriMachine<'tcx> {
             clock: Clock::new(config.isolated_op == IsolatedOp::Allow),
             #[cfg(unix)]
             native_lib: config.native_lib.as_ref().map(|lib_file_path| {
-                let target_triple = tcx.sess.opts.target_triple.triple();
+                let target_triple = tcx.sess.opts.target_triple.tuple();
                 // Check if host target == the session target.
                 if env!("TARGET") != target_triple {
                     panic!(