Fix duplicated word in lsyscache.c comment

Hi Hackers,

While working on a couple of patches that touched lsyscache.c, I noticed a
small typo in a comment:

```
* This is trivially true if they are the same operator. Otherwise, <====
duplicate “Otherwise"
* Otherwise, we look to see if they both belong to an opfamily that
```

So I’m posting a trivial patch to fix it.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/