move passing stage1 compile error tests to stage2

test/cases/compile_errors/ambiguous_decl_reference.zig

@@ -0,0 +1,21 @@
+fn foo() void {}
+fn bar() void {
+    const S = struct {
+        fn baz() void {
+            foo();
+        }
+        fn foo() void {}
+    };
+    S.baz();
+}
+export fn entry() void {
+    bar();
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :5:13: error: ambiguous reference
+// :7:9: note: declared here
+// :1:1: note: also declared here