[FileSystem] Remove `SetFileSystem` method.

This is no longer relevant with the new way we initialize the
FileSystem.

llvm-svn: 346003

lldb/include/lldb/Host/FileSystem.h

@@ -124,9 +124,6 @@ public:
   std::error_code GetRealPath(const llvm::Twine &path,
                               llvm::SmallVectorImpl<char> &output) const;
 
-protected:
-  void SetFileSystem(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs);
-
 private:
   static llvm::Optional<FileSystem> &InstanceImpl();
   llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> m_fs;

lldb/source/Host/common/FileSystem.cpp

@@ -47,10 +47,6 @@ Optional<FileSystem> &FileSystem::InstanceImpl() {
   return g_fs;
 }
 
-void FileSystem::SetFileSystem(IntrusiveRefCntPtr<vfs::FileSystem> fs) {
-  m_fs = fs;
-}
-
 sys::TimePoint<>
 FileSystem::GetModificationTime(const FileSpec &file_spec) const {
   return GetModificationTime(file_spec.GetPath());