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