[clang] [clang-tools-extra] [lldb] [clang] Reland: fix getTemplateInstantiationArgs (PR #208285)

[Nathan Corbyn via cfe-commits]

cofibrant wrote:

> Could you perhaps share a preprocessed TU + command line to help out?  @mizvekov doesn't seem to be able to reproduce this with his own self-build, so it would go a long way to helping us reproduce this.

I'll find some time in the next couple of days

https://github.com/llvm/llvm-project/pull/208285