Support/PathV2: Add filename implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120546 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/PathV2.cpp b/lib/Support/PathV2.cpp
index 7bb7988..9c343ea 100644
--- a/lib/Support/PathV2.cpp
+++ b/lib/Support/PathV2.cpp
@@ -553,6 +553,11 @@
   return make_error_code(errc::success);
 }
 
+error_code filename(const StringRef &path, StringRef &result) {
+  result = *(--end(path));
+  return make_error_code(errc::success);
+}
+
 }
 }
 }