elfclassify: Use (void) for no-argument static functions, not ()

elfclassify: Use (void) for no-argument static functions, not ()

In -std=gnu11 mode gcc will error out on nor argument () static
functions:

src/elfclassify.c:757:1: error: function declaration isn’t a prototype
 [-Werror=strict-prototypes]
  757 | check_checks ()
      | ^~~~~~~~~~~~
src/elfclassify.c: In function ‘check_checks’:
src/elfclassify.c:757:1: error: old-style function definition
 [-Werror=old-style-definition]

This isn't an issue in -std=gnu23 mode (the default with GCC 15):

  A definition using () is not considered an old-style definition in
  C23 mode, because it is equivalent to (void) in that case, but is
  considered an old-style definition for older standards

So just always use (void) instead of () for an empty argument list.

	* src/elfclassify.c (check_checks): Define as check_checks (void).
	(check_ar_members): Define as check_ar_members (void).

Signed-off-by: Mark Wielaard <mark@klomp.org>