Update prebuilt Clang to match Android kernel.

Bug: 132428451
Change-Id: I8f6e2cb23f381fc0c02ddea99b867e58e925e5be
diff --git a/linux-x64/clang/include/llvm/Support/Threading.h b/linux-x64/clang/include/llvm/Support/Threading.h
index e8021f6..23b115f 100644
--- a/linux-x64/clang/include/llvm/Support/Threading.h
+++ b/linux-x64/clang/include/llvm/Support/Threading.h
@@ -1,9 +1,8 @@
 //===-- llvm/Support/Threading.h - Control multithreading mode --*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
 //
 //===----------------------------------------------------------------------===//
 //
@@ -27,7 +26,8 @@
 #define LLVM_THREADING_USE_STD_CALL_ONCE 1
 #elif defined(LLVM_ON_UNIX) &&                                                 \
     (defined(_LIBCPP_VERSION) ||                                               \
-     !(defined(__NetBSD__) || defined(__OpenBSD__) || defined(__ppc__)))
+     !(defined(__NetBSD__) || defined(__OpenBSD__) ||                          \
+       (defined(__ppc__) || defined(__PPC__))))
 // std::call_once from libc++ is used on all Unix platforms. Other
 // implementations like libstdc++ are known to have problems on NetBSD,
 // OpenBSD and PowerPC.