[llvm] llvm: Replace forward declaration with include (PR #171848)

[Jan Svoboda via llvm-commits]

jansvoboda11 wrote:

Your error message doesn't show which `.cpp` file the error originates in, but typically the `.cpp` file that includes `"llvm/Transforms/Instrumentation/SanitizerBinaryMetadata.h‎"` is expected to also include `"llvm/Support/VirtualFileSystem.h"` rather than doing that in the header itself.

https://github.com/llvm/llvm-project/pull/171848