Add ruby_debug_print functions to vm_debug.h

vm_debug.h

@@ -23,8 +23,10 @@ RUBY_SYMBOL_EXPORT_BEGIN
 struct RNode;
 
 VALUE ruby_debug_print_value(int level, int debug_level, const char *header, VALUE v);
+void  ruby_debug_print_v(VALUE v);
 ID    ruby_debug_print_id(int level, int debug_level, const char *header, ID id);
 struct RNode *ruby_debug_print_node(int level, int debug_level, const char *header, const struct RNode *node);
+void  ruby_debug_print_n(const struct RNode *node);
 int   ruby_debug_print_indent(int level, int debug_level, int indent_level);
 void  ruby_debug_gc_check_func(void);
 void ruby_set_debug_option(const char *str);