[clang-tools-extra] [clangd] Don't show inlay hints for __builtin_dump_struct (PR #71366)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> I see; it's a bit unfortunate that such an "invented" call expression gets an ordinary `SourceLocation`.

Out of curiosity, I dialled into today's LLVM [office hours](https://llvm.org/docs/GettingInvolved.html#office-hours) and asked Aaron Ballman about this. He also did not see an obvious way to tell apart the invented `CallExpr`s from regular `CallExpr`s, but suggested that it could be reasonable to just change the code for building the invented `CallExpr`s to give them an invalid SourceLocation (and then our inlay hints code should filter them out without further changes).

https://github.com/llvm/llvm-project/pull/71366