llvm

fc2ce23a - [SYCL RTC] Workaround data race related to the VFS containing toolchain (#20360)

[SYCL RTC] Workaround data race related to the VFS containing toolchain (#20360) This regressed due to https://github.com/intel/llvm/pull/19924 but, apparently, we didn't have proper tests in place. I'm not sure what's causing this exactly, but having each compilation create its unique `ToolchainFS` instead of all of them using the same `llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> SYCLToolchain::ToolchainFS` somehow results in the test (added in this PR) passing consistently.