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