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

third_party/tcmalloc/chromium/src/system-alloc.cc

 // Copyright (c) 2005, 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 148 matching lines @@
   // state) and eventually gets initialized to the specified value.  Note
   // that this code runs for a while before the flags are initialized.
   // That means that even if this flag is set to true, some (initial)
   // memory will be allocated with sbrk before the flag takes effect.
   if (FLAGS_malloc_skip_sbrk) {
     return NULL;
   }
 
   // sbrk will release memory if passed a negative number, so we do
   // a strict check here
-  if (static_cast<ptrdiff_t>(size + alignment) < 0) return NULL;
+  if (static_cast<std::ptrdiff_t>(size + alignment) < 0) return NULL;
 
   // This doesn't overflow because TCMalloc_SystemAlloc has already
   // tested for overflow at the alignment boundary.
   size = ((size + alignment - 1) / alignment) * alignment;
 
   // "actual_size" indicates that the bytes from the returned pointer
   // p up to and including (p + actual_size - 1) have been allocated.
   if (actual_size) {
     *actual_size = size;
   }
@@ skipping 321 matching lines @@
 
 void DumpSystemAllocatorStats(TCMalloc_Printer* printer) {
   for (int j = 0; j < kMaxAllocators; j++) {
     SysAllocator *a = allocators[j];
     if (a == NULL) continue;
     if (a->usable_) {
       a->DumpStats(printer);
     }
   }
 }