[clang] [llvm] [NFC][analyzer] Extract bounds checking library (PR #202372)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

@steakhal @Xazax-hun I replied to all of your (very helpful) review comments, implementing most of the suggested changes. (This involved creating a dozen commits, so on each comment, I replied with a link to the commit that fixes it.)

https://github.com/llvm/llvm-project/pull/202372