Warning fixes from Christos Zoulas

- shadowed variables
- signed/unsigned confusion
- const lossage
- incomplete structure initializations
- unused code

lib/hx509/sel.h

@@ -78,5 +78,5 @@ extern struct hx_expr_input _hx509_expr_input;
 
 int  _hx509_sel_yyparse(void);
 int  _hx509_sel_yylex(void);
-void _hx509_sel_yyerror(char *);
+void _hx509_sel_yyerror(const char *);