Adapt to ISO C23

[ppisar]

A build failed with GCC 15 because that compiler moved to ISO C23 langauge version:

misc.h:32:25: error: ‘bool’ cannot be used here
   32 | char *on_off PROTO((int bool));
  |                         ^~~~

The cause is that ISO C23 added "bool" type. This patchs changes the argument name to match the function definitions.

attributes.c: In function ‘add_attribute’:
attributes.c:552:39: error: passing argument 3 of ‘dl_list_default’ from incompatible pointer type [-Wincompatible-pointer-types]
  552 |     dl_list_default(attr_list, FALSE, destroy_attr_data);
  |                                       ^~~~~~~~~~~~~~~~~
  |                                       |
  |                                       int (*)(attribute_struct *) {aka int (*)(struct _attribute_struct *)}
In file included from attributes.h:15,
	     from attributes.c:10:
dl_list.h:44:34: note: expected ‘int (*)(void)’ but argument is of type ‘int (*)(attribute_struct *)’ {aka ‘int (*)(struct _attribute_struct *)’}
   44 |                            int (*destroy_data)()));
  |                            ~~~~~~^~~~~~~~~~~~~~~

ISO C23 changed meaning of "int foo()" to "int foo(void)". This patch addapts to it.