Merge branch 'vs2017-sdk81' into release-3.14

Merge-request: !2962
diff --git a/Source/cmGlobalVisualStudioVersionedGenerator.cxx b/Source/cmGlobalVisualStudioVersionedGenerator.cxx
index 12d9304..913fc4a 100644
--- a/Source/cmGlobalVisualStudioVersionedGenerator.cxx
+++ b/Source/cmGlobalVisualStudioVersionedGenerator.cxx
@@ -453,7 +453,8 @@
         "HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\"
         "Windows Kits\\Installed Roots;KitsRoot81",
         win81Root, cmSystemTools::KeyWOW64_32)) {
-    return cmSystemTools::FileExists(win81Root + "/um/windows.h", true);
+    return cmSystemTools::FileExists(win81Root + "/include/um/windows.h",
+                                     true);
   }
   return false;
 }