[clang] [clang]Transform uninstantiated ExceptionSpec in TemplateInstantiator (PR #68878)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I'll have to think on this... First blush is that it is fine, but I want a chance to get other opinions as well

https://github.com/llvm/llvm-project/pull/68878