Fix GCC build by using a intptr_t constant instead of anonymous enum.

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3566 matching lines @@
     V(GuardField)                                                              \
     V(TestCids)                                                                \
     V(NumReasons)                                                              \
 
   enum DeoptReasonId {
   #define DEFINE_ENUM_LIST(name) kDeopt##name,
   DEOPT_REASONS(DEFINE_ENUM_LIST)
   #undef DEFINE_ENUM_LIST
   };
 
-  enum {
-    kLastRecordedDeoptReason = kDeoptUnknown - 1
-  };
+  static const intptr_t kLastRecordedDeoptReason = kDeoptUnknown - 1;
 
   enum DeoptFlags {
     // Deoptimization is caused by an optimistically hoisted instruction.
     kHoisted = 1 << 0,
 
     // Deoptimization is caused by an optimistically generalized bounds check.
     kGeneralized = 1 << 1
   };
 
   bool HasDeoptReasons() const { return DeoptReasons() != 0; }
@@ skipping 4074 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_