Add test for crt-static+lto+rwlock issue.

Author: m-ou-se

src/test/ui/issues/issue-94564.rs

@@ -0,0 +1,7 @@
+// run-pass
+// compile-flags: -C lto -C target-feature=+crt-static -C rpath=no -C opt-level=2
+// no-prefer-dynamic
+
+fn main() {
+    let _ = std::process::Command::new("true").spawn();
+}