[clang] [clang] Reject character devices in #embed for now (PR #135370)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> > on Windows we could use something like COM1 on Windows.
> 
> How would that look like?

`#embed "COM1" limit(1)`

But when I try that on my Windows machine, I get a file not found error. Perhaps try `#embed "NUL" limit(1)`?

https://github.com/llvm/llvm-project/pull/135370