[clang] [C++20] [Modules] [Driver] Don't enable -fdelayed-template-parsing by default on windows with C++20 modules (PR #69431)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> Does MSVC have the delayed template parsing effects when using modules? If not, perhaps we should just disable the flag/not allow it to be composed together?

As far as I can reach, (from the issue reports in MSVC community), MSVC don't have problems with the delayed template parsing and the modules. So if our goal of -fdelayed-template-parsing is to keep the same/similar behavior with MSVC, we have a problem now. Given we don't know how to fix the real problem and it indeed affects multiple people now, I think the current patch may be a understandable workaround.

https://github.com/llvm/llvm-project/pull/69431