[clang] [analyzer] Add hack in ArrayBound to cover up missing casts (PR #127117)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

> An interesting thing could be to track in the analyzer the number of suppressed underflows (i.e.: the number of times we resorted to hacking with this solution). That way, we could have more information about how far we deviate from the precise modelling. This could provide a useful metric in the future and may not belong strictly to this patch.

Hm, that could be a good idea, but I'm lazy and I feel that when I need to measure the effects of this suppression, I can just temporarily disable it on a private measurement branch. (This is not a generic measurement that needs to be monitored constantly, it will become relevant just once or twice when we try to make the modelling more precise.) 

https://github.com/llvm/llvm-project/pull/127117