[clang] [Clang][Sema] Disable checking invalid template id in initializer of primary variable template `std::format_kind` with libstdc++ (PR #139560)

[Erich Keane via cfe-commits]

erichkeane wrote:

> I think we should
> 
>     * 1/ Land this patch as is
> 
>     * 2/ Extract the parsing of `__GLIBCXX__` in a separate function
> 
>     * 3/ have a function, probably in Preprocessor (so that it is available from Sema and Parser) such as `IsLibStdCxxBefore(_version_)` that let us do these checks uniformly and are easy to grep for. Ditto for libc++.
> 
> 
> I don't have time at the moment but it would be a useful improvement :)

*4/ Do an audit of all our libcxx hackery in place right now, and apply the new function to it :D  And perhaps instead of `IsLibStdCxxBefore`, be `IsLibStdCxxBetween` :D  Even better if we make it possible to be 'open-ended' in cases where it hasn't been fixed/starts at the beginning of time.

https://github.com/llvm/llvm-project/pull/139560