clang/test/Tooling/clang-check.cpp: Mark it as XFAIL mingw,msvc for now.

It seems JSON parser doesn't like path separator '\' on Win32 hosts.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154017 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Tooling/clang-check.cpp b/test/Tooling/clang-check.cpp
index f3ff43e..3c62487 100644
--- a/test/Tooling/clang-check.cpp
+++ b/test/Tooling/clang-check.cpp
@@ -6,3 +6,6 @@
 // FIXME: Make the above easier.
 
 invalid; // CHECK: C++ requires
+
+// FIXME: JSON doesn't like path separator '\', on Win32 hosts.
+// XFAIL: mingw32,win32