Rename module sys_stat to sys_stat-h. * modules/sys_stat-h: Renamed from modules/sys_stat. * modules/sys_stat-h-tests: Renamed from modules/sys_stat-tests. * modules/sys_stat-h-c++-tests: Renamed from modules/sys_stat-c++-tests. * tests/test-sys_stat-h.c: Renamed from tests/test-sys_stat.c. * tests/test-sys_stat-h-c++.cc: Renamed from tests/test-sys_stat-c++.cc. * doc/posix-headers/sys_stat.texi: Update. * doc/posix-functions/mkdir.texi: Update. * modules/* (Depends-on): Update. * modules/sys_stat: New file.