Added scandir prototype for function pointer with explicitly typed arguments.
Added scandir prototype for function pointer with explicitly typed arguments.

Recent versions of glibc (e.g. 2.10.2) declare scandir having as its
4th argument a pointer to a comparator whose arguments are

	(struct dirent **, struct dirent **) ,

and at least gcc 4.3 will not allow redeclaration using (void *, void *).

This change makes 'configure' look for the expected declaration of
that 4th argument, whose type is available to libfakechroot.c as macro
SCANDIR_TYPE_ARG4 .

blipvert/fakechroot,blipvert/fakechroot-2.9,blipvert/fakechroot,blipvert/fakechroot-2.9,blipvert/fakechroot-2.9,blipvert/fakechroot