third_party/protobuf: update to upstream r371

third_party/protobuf/src/google/protobuf/io/printer.h

Index: third_party/protobuf/src/google/protobuf/io/printer.h
diff --git a/third_party/protobuf/src/google/protobuf/io/printer.h b/third_party/protobuf/src/google/protobuf/io/printer.h
index de0853891b998baabed3ad1b47778b58acf53ce7..5be48543ab04c5cd136ba5b0f916ffcc059892d2 100644
--- a/third_party/protobuf/src/google/protobuf/io/printer.h
+++ b/third_party/protobuf/src/google/protobuf/io/printer.h
@@ -82,7 +82,11 @@ class LIBPROTOBUF_EXPORT Printer {
   // Like the first Print(), except the substitutions are given as parameters.
   void Print(const char* text, const char* variable1, const string& value1,
                                const char* variable2, const string& value2);
-  // TODO(kenton):  Overloaded versions with more variables?  Two seems
+  // Like the first Print(), except the substitutions are given as parameters.
+  void Print(const char* text, const char* variable1, const string& value1,
+                               const char* variable2, const string& value2,
+                               const char* variable3, const string& value3);
+  // TODO(kenton):  Overloaded versions with more variables?  Three seems
   //   to be enough.
 
   // Indent text by two spaces.  After calling Indent(), two spaces will be