Set TARGET_OS_* from GN, falling back to HOST_OS_*.

runtime/vm/dart.cc

 // Copyright (c) 2013, 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/dart.h"
 
 #include "vm/become.h"
 #include "vm/clustered_snapshot.h"
 #include "vm/code_observers.h"
 #include "vm/cpu.h"
@@ skipping 661 matching lines @@
 #define ADD_FLAG(name, isolate_flag, flag)                                     \
   do {                                                                         \
     const bool name = (isolate != NULL) ? isolate->name() : flag;              \
     buffer.AddString(name ? (" " #name) : (" no-" #name));                     \
   } while (0);
     ISOLATE_FLAG_LIST(ADD_FLAG);
 #undef ADD_FLAG
 
 // Generated code must match the host architecture and ABI.
 #if defined(TARGET_ARCH_ARM)
-#if defined(TARGET_ABI_IOS)
+#if defined(TARGET_OS_MACOS) || defined(TARGET_OS_MACOS_IOS)
     buffer.AddString(" arm-ios");
-#elif defined(TARGET_ABI_EABI)
+#else
     buffer.AddString(" arm-eabi");
-#else
-#error Unknown ABI
 #endif
     buffer.AddString(TargetCPUFeatures::hardfp_supported() ? " hardfp"
                                                            : " softfp");
 #elif defined(TARGET_ARCH_ARM64)
     buffer.AddString(" arm64");
 #elif defined(TARGET_ARCH_MIPS)
     buffer.AddString(" mips");
 #elif defined(TARGET_ARCH_IA32)
     buffer.AddString(" ia32");
 #elif defined(TARGET_ARCH_X64)
@@ skipping 70 matching lines @@
   return predefined_handles_->handles_.IsValidScopedHandle(address);
 }
 
 
 bool Dart::IsReadOnlyApiHandle(Dart_Handle handle) {
   ASSERT(predefined_handles_ != NULL);
   return predefined_handles_->api_handles_.IsValidHandle(handle);
 }
 
 }  // namespace dart