System/Path/Windows: Change GetRootDirectory to return file:/// instead of C:/.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118502 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/Win32/Path.inc b/lib/System/Win32/Path.inc
index 8e3004d..75f6b71 100644
--- a/lib/System/Win32/Path.inc
+++ b/lib/System/Win32/Path.inc
@@ -233,9 +233,9 @@
 // FIXME: the following set of functions don't map to Windows very well.
 Path
 Path::GetRootDirectory() {
-  Path result;
-  result.set("C:/");
-  return result;
+  // This is the only notion that that Windows has of a root directory. Nothing
+  // is here except for drives.
+  return Path("file:///");
 }
 
 void