fix format bug for elsestme and stmt def in .g4

src/SysYIRGenerator.h

@@ -20,7 +20,7 @@ public:
   Module *get() const { return module.get(); }
 
 public:
-  std::any visitModule(SysYParser::ModuleContext *ctx) override;
+  std::any visitCompUnit(SysYParser::CompUnitContext *ctx) override;
   std::any visitFuncRParams(SysYParser::FuncRParamsContext *ctx) override;
   std::any visitNumber(SysYParser::NumberContext *ctx) override;
   std::any visitString(SysYParser::StringContext *ctx) override;