Is this a typo?

Hi Hacker,

While working on the other patch and editing heapam.c, I noticed this in line 2251:
```
    /*
* If tuple is cachable, mark it for invalidation from the caches in case
* we abort. Note it is OK to do this after releasing the buffer, because
* the heaptup data structure is all in local memory, not in the shared
* buffer.
*/
```

Is “cachable” a typo? I confirmed with a dictionary and it gave me “cacheable”. Maybe an acceptable old usage that I am
notaware of? So, I want to confirm with the community. 

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