additional includes needed for MIPS toolchain after move of hashmap

src/base/hashmap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The reason we write our own hash map instead of using unordered_map in STL,
 // is that STL containers use a mutex pool on debug build, which will lead to
 // deadlock when we are using async signal handler.
 
 #ifndef V8_BASE_HASHMAP_H_
 #define V8_BASE_HASHMAP_H_
 
+#include <stdlib.h>
+
 #include "src/base/bits.h"
 #include "src/base/logging.h"
 
 namespace v8 {
 namespace base {
 
 class DefaultAllocationPolicy {
  public:
   V8_INLINE void* New(size_t size) { return malloc(size); }
   V8_INLINE static void Delete(void* p) { free(p); }
@@ skipping 319 matching lines @@
       return Iterator(this, this->LookupOrInsert(key, key->Hash(), allocator));
     }
     return Iterator(this, this->Lookup(key, key->Hash()));
   }
 };
 
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_HASHMAP_H_