Lift VFS from clang to llvm (NFC)

This patch moves the virtual file system form clang to llvm so it can be
used by more projects.

Concretely the patch:
 - Moves VirtualFileSystem.{h|cpp} from clang/Basic to llvm/Support.
 - Moves the corresponding unit test from clang to llvm.
 - Moves the vfs namespace from clang::vfs to llvm::vfs.
 - Formats the lines affected by this change, mostly this is the result of
   the added llvm namespace.

RFC on the mailing list:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/126657.html

Differential revision: https://reviews.llvm.org/D52783

llvm-svn: 344140

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/Lex/PTHLexer.cpp b/clang/lib/Lex/PTHLexer.cpp
index 45cff56dcaa..74c7c5ea7e8 100644
--- a/clang/lib/Lex/PTHLexer.cpp
+++ b/clang/lib/Lex/PTHLexer.cpp
@@ -715,8 +715,8 @@ public:
               FL.getBase()) {}
 
   LookupResult getStat(StringRef Path, FileData &Data, bool isFile,
-                       std::unique_ptr<vfs::File> *F,
-                       vfs::FileSystem &FS) override {
+                       std::unique_ptr<llvm::vfs::File> *F,
+                       llvm::vfs::FileSystem &FS) override {
     // Do the lookup for the file's data in the PTH file.
     CacheTy::iterator I = Cache.find(Path);