volser: use OS_CLOSE() instead of close()

Use OS_CLOSE() instead of close() when closing vol package
allocated file descriptors.  On Windows, close() != nt_close().

Change-Id: I5737c0e4e83534bd5f4183dde195c4b8091474c1
Reviewed-on: http://gerrit.openafs.org/3668
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>

src/volser/volprocs.c

@@ -136,7 +136,7 @@ VPFullUnlock_r(void)
     struct DiskPartition64 *tp;
     for (tp = DiskPartitionList; tp; tp = tp->next) {
 	if (tp->lock_fd != INVALID_FD) {
-	    close(tp->lock_fd);	/* releases flock held on this partition */
+            OS_CLOSE(tp->lock_fd);
 	    tp->lock_fd = INVALID_FD;
 	}
     }