Unify comments style

- Change /* comments */ to // comments
- Re-generate auto-generated files
- Remove legacy unused GEMMINC SSE micro-kernels

PiperOrigin-RevId: 271901989
diff --git a/src/x8-zip/x3-scalar.c b/src/x8-zip/x3-scalar.c
index b4319ef..485c1cc 100644
--- a/src/x8-zip/x3-scalar.c
+++ b/src/x8-zip/x3-scalar.c
@@ -1,9 +1,7 @@
-/*
- * Copyright 2019 Google LLC
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree.
- */
+// Copyright 2019 Google LLC
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
 
 #include <assert.h>