versioner: Port to clang-r344140

This commit updates bionic versioner to use clang-r344140.  To be
specific, this commit renames `clang::vfs::FileSystem` to
`llvm::vfs::FileSystem` and updates the headers.

Bug: 111759196
Test: bionic/tools/versioner/run_tests.py
Change-Id: I304ecae79da5a1638ae755dac92b52e314019cf1
diff --git a/tools/versioner/src/VFS.cpp b/tools/versioner/src/VFS.cpp
index 8f9de88..d797f82 100644
--- a/tools/versioner/src/VFS.cpp
+++ b/tools/versioner/src/VFS.cpp
@@ -25,14 +25,14 @@
 #include <string>
 
 #include <android-base/unique_fd.h>
-#include <clang/Basic/VirtualFileSystem.h>
 #include <llvm/ADT/IntrusiveRefCntPtr.h>
 #include <llvm/Support/MemoryBuffer.h>
+#include <llvm/Support/VirtualFileSystem.h>
 
 #include "Utils.h"
 
 using android::base::unique_fd;
-using namespace clang::vfs;
+using namespace llvm::vfs;
 
 static void addDirectoryToVFS(InMemoryFileSystem* vfs, const std::string& path) {
   char* paths[] = { const_cast<char*>(path.c_str()), nullptr };