Move the builtin headers to use the new license file header.

Summary:
These all had somewhat custom file headers with different text from the
ones I searched for previously, and so I missed them. Thanks to Hal and
Kristina and others who prompted me to fix this, and sorry it took so
long.

Reviewers: hfinkel

Subscribers: mcrosier, javed.absar, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60406

llvm-svn: 357941
diff --git a/clang/lib/Headers/unwind.h b/clang/lib/Headers/unwind.h
index 438f914..029524b 100644
--- a/clang/lib/Headers/unwind.h
+++ b/clang/lib/Headers/unwind.h
@@ -1,22 +1,8 @@
 /*===---- unwind.h - Stack unwinding ----------------------------------------===
  *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  *
  *===-----------------------------------------------------------------------===
  */