[clang] [Clang] fix range calculation for conditionals with throw expressions (PR #112081)

[Erich Keane via cfe-commits]

erichkeane wrote:

The sanitizer failures are likely unrelated to this, but the self-build of the Flang sources might be?  Do we have evidence of those failing on other commits? 

https://github.com/llvm/llvm-project/pull/112081