move passing stage1 compile error tests to stage2

test/cases/compile_errors/duplicate_struct_field.zig

@@ -0,0 +1,16 @@
+const Foo = struct {
+    Bar: i32,
+    Bar: usize,
+};
+export fn entry() void {
+    const a: Foo = undefined;
+    _ = a;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:5: error: duplicate struct field: 'Bar'
+// :2:5: note: other field here
+// :1:13: note: struct declared here