Revert "remove host & target attributes"

This reverts commit 5a051eb.

Author: Freax13

src/cargo/core/compiler/compilation.rs

@@ -69,6 +69,9 @@ pub struct Compilation<'cfg> {
     /// Flags to pass to rustdoc when invoked from cargo test, per package.
     pub rustdocflags: HashMap<PackageId, Vec<String>>,
 
+    pub host: String,
+    pub target: String,
+
     config: &'cfg Config,
 
     /// Rustc process to be used by default
@@ -126,6 +129,8 @@ impl<'cfg> Compilation<'cfg> {
             rustc_process: rustc,
             rustc_workspace_wrapper_process,
             primary_rustc_process,
+            host: bcx.host_triple().to_string(),
+            target: bcx.target_data.short_name(&default_kind).to_string(),
             target_runner: target_runner(bcx, default_kind)?,
         })
     }

src/cargo/ops/cargo_test.rs

@@ -144,7 +144,7 @@ fn run_doc_tests(
     let mut runtool: &Option<(std::path::PathBuf, Vec<String>)> = &None;
     if doctest_xcompile {
         runtool = compilation.target_runner();
-    } else if options.compile_opts.build_config.requested_kind.is_host() {
+    } else if compilation.host != compilation.target {
         return Ok((Test::Doc, errors));
     }