Added PR number for failing win64 tests.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177886 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Tooling/auto-detect-from-source-parent-of-cwd.cpp b/test/Tooling/auto-detect-from-source-parent-of-cwd.cpp
index f4ffba7..6b632b0 100644
--- a/test/Tooling/auto-detect-from-source-parent-of-cwd.cpp
+++ b/test/Tooling/auto-detect-from-source-parent-of-cwd.cpp
@@ -8,4 +8,5 @@
 invalid;
 
 // REQUIRES: shell
+// PR15590
 // XFAIL: win64