Try harder to supress the test from r212975 on Windows

The attempt in r212980 was broken because we might not fail if
LLVM_ON_UNIX is enabled for cross compiling to Windows, and it didn't
consider mingw either.

llvm-svn: 212989
diff --git a/clang/test/Modules/inferred-framework-case.m b/clang/test/Modules/inferred-framework-case.m
index a38a08d..e511155 100644
--- a/clang/test/Modules/inferred-framework-case.m
+++ b/clang/test/Modules/inferred-framework-case.m
@@ -1,7 +1,7 @@
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -F %S/Inputs %s -verify -DA
-// FIXME: getCanonicalName() is not implemented on Windows.
-// XFAIL: win32
+// FIXME: PR20299 - getCanonicalName() is not implemented on Windows.
+// REQUIRES: shell
 
 @import MOdule; // expected-error{{module 'MOdule' not found}}
 @import Module;