Ensure that sanitizer runtimes are built for all our supported x86_64
platforms.

Now that we patch in our own custom -cros and -pc targets instead
of falling back to -unknown, we need to add builds for those
targets as well to allow the linker to find the correct versions
of the librustc_[almt]san static libraries.

diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index a796685f9dd..20a7f0d8e59 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -660,7 +660,7 @@ fn supported_sanitizers(out_dir: &Path, target: Interned<String>) -> Vec<Sanitiz
                 });
             }
         }
-        "x86_64-unknown-linux-gnu" => {
+        "x86_64-unknown-linux-gnu" | "x86_64-cros-linux-gnu" | "x86_64-pc-linux-gnu" => {
             for s in &["asan", "lsan", "msan", "tsan"] {
                 result.push(SanitizerRuntime {
                     cmake_target: format!("clang_rt.{}-x86_64", s),