volume_inline.h does not need sys/file.h

volume_inline.h does not need sys/file.h

src/vol/volume_inline.h does not need sys/file.h; at one point, it was
using macros from sys/file.h for locking constants, but now we use the
lwp/lock.h constants. So, include that instead. Also, only include it
for DAFS, since we only use the constants in the DAFS case. Thanks,
Jeffrey Altman.

Change-Id: I114b438d7fb1fbb3a35bdfa0717ac334c7f80355
Reviewed-on: http://gerrit.openafs.org/1596
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>