message: windows: antlr4 dissable C4251 warning
diff: #ifdef _MSC_VER
  #pragma warning (disable: 4250) // Class inherits by dominance.
  #pragma warning (disable: 4512) // assignment operator could not be generated
  -
  + #pragma warning (disable: 4251) // needs to have dll-interface to be used by clients of class
  #if _MSC_VER < 1900
  // Before VS 2015 code like "while (true)" will create a (useless) warning in level 4.
  #pragma warning (disable: 4127) // conditional expression is constant
  