clang/test/Tooling/clang-check-pwd.cpp: Add "REQUIRES: shell".

This passes on MSYS bash and Cygwin.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156929 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Tooling/clang-check-pwd.cpp b/test/Tooling/clang-check-pwd.cpp
index cb94344..a8047a9 100644
--- a/test/Tooling/clang-check-pwd.cpp
+++ b/test/Tooling/clang-check-pwd.cpp
@@ -8,6 +8,4 @@
 // CHECK: C++ requires
 invalid;
 
-// FIXME: JSON doesn't like path separator '\', on Win32 hosts.
-// FIXME: clang-check doesn't like gcc driver on cygming.
-// XFAIL: cygwin,mingw32,win32
+// REQUIRES: shell