New comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/24424#issuecomment-785048370

Comment:
If compilers depend only on `isl15`, why isn't it possible to just update `isl` and `cloog` and leave `isl15` alone?

I mean: `cloog` has to be revbumped for the updated `isl`, but the (cross) compilers can be left alone, they shouldn't be affected at all by this change.

What am I missing?
@pullmoll @dkwo