Log Message:
protobuf: update to 3.11.4.

2020-02-14 version 3.11.4 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)

  C#
  * Fix latest ArgumentException for C# extensions (#7188)
  * Enforce recursion depth checking for unknown fields (#7210)

  Ruby
  * Fix wrappers with a zero value (#7195)
  * Fix JSON serialization of 0/empty-valued wrapper types (#7198)