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/Driver.h b/tools/versioner/src/Driver.h
index 48683e4..99e57ae 100644
--- a/tools/versioner/src/Driver.h
+++ b/tools/versioner/src/Driver.h
@@ -31,10 +31,10 @@
   std::vector<std::string> dependencies;
 };
 
-void initializeTargetCC1FlagCache(llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem> vfs,
+void initializeTargetCC1FlagCache(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs,
                                   const std::set<CompilationType>& types,
                                   const std::unordered_map<Arch, CompilationRequirements>& reqs);
 
-void compileHeader(llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem> vfs,
+void compileHeader(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs,
                    HeaderDatabase* header_database, CompilationType type,
                    const std::string& filename);