move stage2 compile errors out of special folder

test/cases/compile_errors/struct_duplicate_field_name.zig

@@ -0,0 +1,16 @@
+const S = struct {
+    foo: u32,
+    foo: u32,
+};
+
+export fn entry() void {
+    const s: S = .{ .foo = 100 };
+    _ = s;
+}
+
+// error
+// target=native
+//
+// :3:5: error: duplicate struct field: 'foo'
+// :2:5: note: other field here
+// :1:11: note: struct declared here