Add regression test for #70673

Author: Oliver Scherer

src/test/ui/issues/issue-70673.rs

@@ -0,0 +1,12 @@
+// Regression test for https://github.com/rust-lang/rust/issues/70673.
+
+// run-pass
+
+#![feature(thread_local)]
+
+#[thread_local]
+static A: &u8 = &42;
+
+fn main() {
+    dbg!(*A);
+}