FYI: master: C++: symbol constructors: add a missing reference

[Akim Demaille]

Will be installed in a couple of days.

commit d7b391ec2c4027fae458c096fe4de886706ada7d
Author: Akim Demaille <akim.demai...@gmail.com>
Date:   Sun Aug 12 17:48:08 2018 +0200

    C++: symbol constructors: add a missing reference
    
    Fix a typo so that instead of
    
        basic_symbol::basic_symbol (typename Base::kind_type t, const int v)
    
    we now generate
    
        basic_symbol::basic_symbol (typename Base::kind_type t, const int& v)
    
    * data/variant.hh (b4_basic_symbol_constructor_declare)
    (b4_basic_symbol_constructor_define): Add missing reference.

diff --git a/data/variant.hh b/data/variant.hh
index f3dee535..990d14d2 100644
--- a/data/variant.hh
+++ b/data/variant.hh
@@ -334,7 +334,7 @@ m4_define([b4_basic_symbol_constructor_declare],
 [[
   basic_symbol (]b4_join(
           [typename Base::kind_type t],
-          b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]),
+          b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[& v]),
           b4_locations_if([const location_type& l]))[);
 ]])
 
@@ -346,7 +346,7 @@ m4_define([b4_basic_symbol_constructor_define],
   template <typename Base>
   ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
           [typename Base::kind_type t],
-          b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]),
+          b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[& v]),
           b4_locations_if([const location_type& l]))[)
     : Base (t)]b4_symbol_if([$1], [has_type], [
     , value (v)])[]b4_locations_if([