c++: fix printing of state number on streams

Avoid this kind of display:

    LAC: checking lookahead identifier: R4 R3 G^B S5

* data/skeletons/lalr1.cc: Convert state_t to int before printing it.

data/skeletons/lalr1.cc

@@ -1418,7 +1418,7 @@ b4_dollar_popdef])[]dnl
                      : yylac_stack_.back ());
         // Push the resulting state of the reduction.
         state_type state = yy_lr_goto_state_ (top_state, yyr1_[yyrule]);
-        YYCDEBUG << " G" << state;
+        YYCDEBUG << " G" << int (state);
         yylac_stack_.push_back (state);
       }
   }