c++: minor changes

* data/lalr1.cc: Fix oldish comment.
* data/stack.hh: Prefer typename for type names.
Use size() instead of duplicating it.
* examples/variant-11.yy, examples/variant.yy (yylex): Use int,
as this is the type of the semantic value.

doc/bison.texi

@@ -11723,7 +11723,7 @@ The rules are simple.  The driver is used to report errors.
   if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))
     throw yy::parser::syntax_error (loc, "integer is out of range: "
                                     + std::string(yytext));
-  return yy::parser::make_NUMBER (n, loc);
+  return yy::parser::make_NUMBER (int (n), loc);
 @}
 @end group
 @{id@}       return yy::parser::make_IDENTIFIER (yytext, loc);