[FileSystem] Open File instances through the FileSystem.

This patch modifies how we open File instances in LLDB. Rather than
passing a path or FileSpec to the constructor, we now go through the
virtual file system. This is needed in order to make things work with
the VFS in the future.

Differential revision: https://reviews.llvm.org/D54020

llvm-svn: 346049

lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp

@@ -829,11 +829,15 @@ bool ScriptInterpreterPython::ExecuteOneLine(
                                                  error_file_sp);
     } else {
       input_file_sp.reset(new StreamFile());
-      input_file_sp->GetFile().Open(FileSystem::DEV_NULL,
-                                    File::eOpenOptionRead);
+      FileSystem::Instance().Open(input_file_sp->GetFile(),
+                                  FileSpec(FileSystem::DEV_NULL),
+                                  File::eOpenOptionRead);
+
       output_file_sp.reset(new StreamFile());
-      output_file_sp->GetFile().Open(FileSystem::DEV_NULL,
-                                     File::eOpenOptionWrite);
+      FileSystem::Instance().Open(output_file_sp->GetFile(),
+                                  FileSpec(FileSystem::DEV_NULL),
+                                  File::eOpenOptionWrite);
+
       error_file_sp = output_file_sp;
     }