Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/stubs/stringpiece.h

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // 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.
@@ skipping 204 matching lines @@
       length_ = CheckedSsizeTFromSizeT(strlen(str));
     }
   }
 
   template <class Allocator>
   StringPiece(  // NOLINT(runtime/explicit)
       const std::basic_string<char, std::char_traits<char>, Allocator>& str)
       : ptr_(str.data()), length_(0) {
     length_ = CheckedSsizeTFromSizeT(str.size());
   }
+#if defined(HAS_GLOBAL_STRING)
+  template <class Allocator>
+  StringPiece(  // NOLINT(runtime/explicit)
+      const basic_string<char, std::char_traits<char>, Allocator>& str)
+      : ptr_(str.data()), length_(0) {
+    length_ = CheckedSsizeTFromSizeT(str.size());
+  }
+#endif
 
   StringPiece(const char* offset, stringpiece_ssize_type len)
       : ptr_(offset), length_(len) {
     assert(len >= 0);
   }
 
   // Substring of another StringPiece.
   // pos must be non-negative and <= x.length().
   StringPiece(StringPiece x, stringpiece_ssize_type pos);
   // Substring of another StringPiece.
@@ skipping 239 matching lines @@
     size_t result = 0;
     for (const char *str = s.data(), *end = str + s.size(); str < end; str++) {  
       result = 5 * result + *str;
     }
     return result;
   }
 };
 GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END
 
 #endif  // STRINGS_STRINGPIECE_H_