[clang] [Clang] Fix immediate escalation of template function specializations. (PR #124404)

[Nikita Popov via cfe-commits]

nikic wrote:

FYI this change has some measurable compile-time overhead (about 0.2% for debug builds): https://llvm-compile-time-tracker.com/compare.php?from=eaa5897534cbd263d0cdbf780f72133c2fe8d8d4&to=561132e71b29d9b747dfda1509f715847852f77b&stat=instructions:u

Not sure whether that's expected or not.

https://github.com/llvm/llvm-project/pull/124404