Update vmware/govmomi vendor: add vapi package

Zones implementation for vSphere cloud provider needs dependencies
which are not included in current vmware/govmomi vendor. So this
update added "vapi" package to support zones.

vendor/github.com/vmware/govmomi/simulator/os_unix.go

@@ -29,12 +29,10 @@ func (ds *Datastore) stat() error {
 		return err
 	}
 
-	bsize := uint64(stat.Bsize) / 512
-
-	info.FreeSpace = int64(stat.Bfree*bsize) >> 1
+	info.FreeSpace = int64(stat.Bfree * uint64(stat.Bsize))
 
 	ds.Summary.FreeSpace = info.FreeSpace
-	ds.Summary.Capacity = int64(stat.Blocks*bsize) >> 1
+	ds.Summary.Capacity = int64(stat.Blocks * uint64(stat.Bsize))
 
 	return nil
 }