[clang] Remove `DirectoryEntry::getName()`

[jansvoboda11]

Summary

This patch finally removes the deprecated DirectoryEntry::getName() function.

Depends on D151927.

[benlangmuir]

Given this was a commonly used function before and there's a decent chance it's used out of tree somewhere, should we wait until the next llvm release branch has been cut before landing this?

[jansvoboda11]

Yes, I'd like to get the deprecation (and fixes in other LLVM sub-projects) into main ASAP and then land this patch after the branch for the 17 release is cut.

clang/include/clang/Basic/DirectoryEntry.h

 /// Cached information about one directory (either on disk or in
 /// the virtual file system).
 class DirectoryEntry {
   DirectoryEntry() = default;
   DirectoryEntry(const DirectoryEntry &) = delete;
   DirectoryEntry &operator=(const DirectoryEntry &) = delete;
   friend class FileManager;
   friend class FileEntryTestHelper;
-
-  // FIXME: We should not be storing a directory entry name here.
-  StringRef Name; // Name of the directory.
-
-public:
-  LLVM_DEPRECATED("Use DirectoryEntryRef::getName() instead.", "")
-  StringRef getName() const { return Name; }
 };
 
 /// A reference to a \c DirectoryEntry  that includes the name of the directory
 /// as it was accessed by the FileManager's client.
 class DirectoryEntryRef {
 public:
   const DirectoryEntry &getDirEntry() const { return *ME->getValue(); }
 

clang/lib/Basic/FileManager.cpp

void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
   // at the same time.  Therefore, if DirName is already in the cache,
   // we don't need to recurse as its ancestors must also already be in
   // the cache (or it's a known non-virtual directory).
   if (NamedDirEnt.second)
     return;
 
   // Add the virtual directory to the cache.
   auto *UDE = new (DirsAlloc.Allocate()) DirectoryEntry();
-  UDE->Name = NamedDirEnt.first();
   NamedDirEnt.second = *UDE;
   VirtualDirectoryEntries.push_back(UDE);
 
   // Recursively add the other ancestors.
   addAncestorsAsVirtualDirs(DirName);
 }
 
 llvm::Expected<DirectoryEntryRef>
FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
   // symlinked to another, for example) or the same path (on
   // Windows).
   DirectoryEntry *&UDE = UniqueRealDirs[Status.getUniqueID()];
 
   if (!UDE) {
     // We don't have this directory yet, add it.  We use the string
     // key from the SeenDirEntries map as the string.
     UDE = new (DirsAlloc.Allocate()) DirectoryEntry();
-    UDE->Name = InterndDirName;
   }
   NamedDirEnt.second = *UDE;
 
   return DirectoryEntryRef(NamedDirEnt);
 }
 
 llvm::ErrorOr<const DirectoryEntry *>
 FileManager::getDirectory(StringRef DirName, bool CacheFailure) {