Replaced ptrdiff_t with std::ptrdiff_t in all files to enable build with gcc-4.6.0.

third_party/tcmalloc/chromium/src/base/stl_allocator.h

 /* Copyright (c) 2006, Google Inc.
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  * 
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 41 matching lines @@
 //
 // Usage example:
 //   set<T, less<T>, STL_Allocator<T, MyAlloc> > my_set;
 // CAVEAT: Parts of the code below are probably specific
 //         to the STL version(s) we are using.
 //         The code is simply lifted from what std::allocator<> provides.
 template <typename T, class Alloc>
 class STL_Allocator {
  public:
   typedef size_t     size_type;
-  typedef ptrdiff_t  difference_type;
+  typedef std::ptrdiff_t  difference_type;
   typedef T*         pointer;
   typedef const T*   const_pointer;
   typedef T&         reference;
   typedef const T&   const_reference;
   typedef T          value_type;
 
   template <class T1> struct rebind {
     typedef STL_Allocator<T1, Alloc> other;
   };
 
@@ skipping 14 matching lines @@
   size_type max_size() const { return size_t(-1) / sizeof(T); }
 
   void construct(pointer p, const T& val) { ::new(p) T(val); }
   void destroy(pointer p) { p->~T(); }
 
   // There's no state, so these allocators are always equal
   bool operator==(const STL_Allocator&) const { return true; }
 };
 
 #endif  // BASE_STL_ALLOCATOR_H_