[clang] [clang][ASTImporter] Improve structural equivalence of overloadable operators. (PR #72242)

[Balázs Kéri via cfe-commits]

balazske wrote:

I have updated the comment.
Probably I can test it with more projects after the other fixes with variable templates (#72841) are finished, then there may be less crashes.

https://github.com/llvm/llvm-project/pull/72242