[clang] [BoundsSafety] Allow 'counted_by' attribute on pointers in structs in C (PR #90786)

[Bill Wendling via cfe-commits]

bwendling wrote:

Thank you. I wrote to the author. I hope he'll be able to come up with a change on his end. Or at least an explanation that makes sense :-)

https://github.com/llvm/llvm-project/pull/90786