* libc/posix/scandir.c (DIRSIZ, scandir): use struct dirent.d_namlen
only if _DIRENT_HAVE_D_NAMLEN is defined.
(alphasort): aligned prototype with
libc/sys/cygwin/sys/dirent.h and simplified function body.
* libc/posix/telldir.c (telldir): changed "telldir" prototype to
long telldir (DIR *) as mentioned in annex B of POSIX.1