Fix -INT_MIN integer overflow in itoa_r().

base/third_party/symbolize/symbolize.cc

 // 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 633 matching lines @@
     buf[0] = '\000';
     return NULL;
   }
 
   char *start = buf;
 
   uintptr_t j = i;
 
   // Handle negative numbers (only for base 10).
   if (i < 0 && base == 10) {
-    j = -i;
+    // This does "j = -i" while avoiding integer overflow.
+    j = static_cast<uintptr_t>(-(i + 1)) + 1;
 
     // Make sure we can write the '-' character.
     if (++n > sz) {
       buf[0] = '\000';
       return NULL;
     }
     *start++ = '-';
   }
 
   // Loop until we have converted the entire number. Output at least one
@@ skipping 174 matching lines @@
 
 // TODO: Support other environments.
 bool Symbolize(void *pc, char *out, int out_size) {
   assert(0);
   return false;
 }
 
 _END_GOOGLE_NAMESPACE_
 
 #endif