* modules/tmpdir (Depends-on): Add sys_stat. * modules/mkdtemp (Depends-on): Add tempname, drop unistd. * lib/mkdtemp.c (gen_tempname): Remove; tempname covers this. * lib/tmpdir.c (S_ISDIR): Simplify, thanks to sys_stat. * m4/mkdtemp.m4 (gl_PREREQ_MKDTEMP): Simplify, thanks to tempname.