* include/dotlock.h: New.  From current gnupg master.
* util/dotlock.c: Ditto.  Include util.h.  The major changes done in
master are: Factor Unix and W32 specific code out into specific
functions.  Define HAVE_POSIX_SYSTEM.  Rearrange some functions.
(disable_dotlock): Rename to dotlock_disable.
(create_dotlock): Rename to dotlock_create and add a dummy arg.
(destroy_dotlock): Rename to dotlock_destroy.
(make_dotlock): Rename to dotlock_take.
(release_dotlock): Rename to dotlock_release.
(remove_lockfiles): Rename to dotlock_remove_lockfiles.