Adds support for building arm64 Android.

runtime/vm/os_android.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_OS_ANDROID)
 
 #include "vm/os.h"
 
 #include <android/log.h>  // NOLINT
@@ skipping 187 matching lines @@
 
 
 void OS::AlignedFree(void* ptr) {
   free(ptr);
 }
 
 
 // TODO(5411554):  May need to hoist these architecture dependent code
 // into a architecture specific file e.g: os_ia32_linux.cc
 intptr_t OS::ActivationFrameAlignment() {
-#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
+#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64) || \
+    defined(TARGET_ARCH_ARM64)
   const int kMinimumAlignment = 16;
 #elif defined(TARGET_ARCH_ARM)
   const int kMinimumAlignment = 8;
 #else
 #error Unsupported architecture.
 #endif
   intptr_t alignment = kMinimumAlignment;
   // TODO(5411554): Allow overriding default stack alignment for
   // testing purposes.
   // Flags::DebugIsInt("stackalign", &alignment);
   ASSERT(Utils::IsPowerOfTwo(alignment));
   ASSERT(alignment >= kMinimumAlignment);
   return alignment;
 }
 
 
 intptr_t OS::PreferredCodeAlignment() {
-#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
+#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64) || \
+    defined(TARGET_ARCH_ARM64)
   const int kMinimumAlignment = 16;
 #elif defined(TARGET_ARCH_ARM)
   const int kMinimumAlignment = 16;
 #else
 #error Unsupported architecture.
 #endif
   intptr_t alignment = kMinimumAlignment;
   // TODO(5411554): Allow overriding default code alignment for
   // testing purposes.
   // Flags::DebugIsInt("codealign", &alignment);
@@ skipping 176 matching lines @@
 }
 
 
 void OS::Exit(int code) {
   exit(code);
 }
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_ANDROID)