message: appveyor use antlr4.8
diff: @@ -15,7 +15,7 @@ environment:
  install:
  - 'git submodule update --init --recursive'
  - - "curl -fsS -o antlr4-complete.jar https://www.antlr.org/download/antlr-4.7.2-complete.jar"
  + - "curl -fsS -o antlr4-complete.jar https://www.antlr.org/download/antlr-4.8-complete.jar"
  - "git clone https://github.com/antlr/antlr4"
  - "cd antlr4/runtime/Cpp"
  - "mkdir build"
  