Rename target triple to target tuple in many places in the compiler

This changes the naming to the new naming, used by `--print
target-tuple`.
It does not change all locations, but many.

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -47,7 +47,7 @@ pub(crate) fn get_linker<'a>(
     self_contained: bool,
     target_cpu: &'a str,
 ) -> Box<dyn Linker + 'a> {
-    let msvc_tool = windows_registry::find_tool(sess.opts.target_triple.triple(), "link.exe");
+    let msvc_tool = windows_registry::find_tool(sess.opts.target_triple.tuple(), "link.exe");
 
     // If our linker looks like a batch script on Windows then to execute this
     // we'll need to spawn `cmd` explicitly. This is primarily done to handle