fcntl-h: support GNU flags like O_IGNORE_CTTY

fcntl-h: support GNU flags like O_IGNORE_CTTY

* doc/posix-headers/fcntl.texi (fcntl.h): Support O_IGNORE_CTTY,
O_NOLINK, and O_NOTRANS.  These flags are nonzero on GNU/Hurd
systems.  Discovered when using fcntl-h with GNU Emacs, which uses
O_IGNORE_CTTY.  Fix misspelling of F_SETLKW.
* lib/fcntl.in.h (O_IGNORE_CTTY, O_NOLINK, O_NOTRANS):
Define to 0 if not already defined.
* tests/test-fcntl-h.c: Test these new flags.