`_gtime _t` does not zero-fill as in `HHMMSS` format

```k
t: -392059337
(24 60 60 _vsx t ! 86400)
100 _sv (24 60 60 _vsx t ! 86400)
_gtime t
```
outputs
```
6 37 43
63743
20220731 63743
```

The HHMMSS section `63743` (6 37 43) should be zero-filled like this `063743` (06 37 43)
I think `_sv` implementation is related to this.