vol: fix OS_LOCKFILE/OS_UNLOCKFILE for Windows

vol: fix OS_LOCKFILE/OS_UNLOCKFILE for Windows

On UNIX the OS_LOCKFILE and OS_UNLOCKFILE macros return zero
on success.  Since Windows LockFile() and UnlockFile() return
non-zero (TRUE) on success, negate the return value as part
of the macro definition.

Change-Id: Icb4c8555de9a16fdfddcaeb9ede28bbd401e76b7
Reviewed-on: http://gerrit.openafs.org/3664
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>