[clang] mark the tokens for pragma export as reinjected (PR #177979)

[Erich Keane via cfe-commits]

erichkeane wrote:

> @erichkeane, Could you try out the asan build on this. I'm try to do an asan build too but it's the first time on this system so it might take me a bit. Thanks

I don't have one built/setup either.  Perhaps @mikaelholmen could? 

https://github.com/llvm/llvm-project/pull/177979