Tests: Add missing include in testUVProcessChainHelper on Windows

We use `STATUS_ACCESS_VIOLATION` from `windows.h`.

Tests/CMakeLib/testUVProcessChainHelper.cxx

diff --git a/Tests/CMakeLib/testUVProcessChainHelper.cxx b/Tests/CMakeLib/testUVProcessChainHelper.cxx
index b53cac4..1b4adb7 100644
--- a/Tests/CMakeLib/testUVProcessChainHelper.cxx
+++ b/Tests/CMakeLib/testUVProcessChainHelper.cxx
@@ -9,6 +9,10 @@
 
 #include "cmSystemTools.h"
 
+#ifdef _WIN32
+#  include <windows.h>
+#endif
+
 static std::string getStdin()
 {
   char buffer[1024];