Rename Windows.h to WindowsSupport.h to avoid ambiguity

llvm-svn: 201258
diff --git a/llvm/lib/Support/Threading.cpp b/llvm/lib/Support/Threading.cpp
index 13fba2e..9d7ac6c 100644
--- a/llvm/lib/Support/Threading.cpp
+++ b/llvm/lib/Support/Threading.cpp
@@ -103,7 +103,7 @@
   ::pthread_attr_destroy(&Attr);
 }
 #elif LLVM_ENABLE_THREADS!=0 && defined(LLVM_ON_WIN32)
-#include "Windows/Windows.h"
+#include "Windows/WindowsSupport.h"
 #include <process.h>
 
 struct ThreadInfo {