Remove base's ALIGNOF/ALIGNAS in favor of alignof/alignas.

base/process/launch_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/process/launch.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
@@ skipping 693 matching lines @@
 #endif
 NOINLINE pid_t CloneAndLongjmpInChild(unsigned long flags,
                                       pid_t* ptid,
                                       pid_t* ctid,
                                       jmp_buf* env) {
   // We use the libc clone wrapper instead of making the syscall
   // directly because making the syscall may fail to update the libc's
   // internal pid cache. The libc interface unfortunately requires
   // specifying a new stack, so we use setjmp/longjmp to emulate
   // fork-like behavior.
-  char stack_buf[PTHREAD_STACK_MIN] ALIGNAS(16);
+  alignas(16) char stack_buf[PTHREAD_STACK_MIN];
 #if defined(ARCH_CPU_X86_FAMILY) || defined(ARCH_CPU_ARM_FAMILY) || \
     defined(ARCH_CPU_MIPS_FAMILY)
   // The stack grows downward.
   void* stack = stack_buf + sizeof(stack_buf);
 #else
 #error "Unsupported architecture"
 #endif
   return clone(&CloneHelper, stack, flags, env, ptid, nullptr, ctid);
 }
 
@@ skipping 33 matching lines @@
   jmp_buf env;
   if (setjmp(env) == 0) {
     return CloneAndLongjmpInChild(flags, ptid, ctid, &env);
   }
 
   return 0;
 }
 #endif  // defined(OS_LINUX) || defined(OS_NACL_NONSFI)
 
 }  // namespace base