Revise include order using clang-format-6.0

Run the `clang-format.bash` script to update our C and C++ code to a new
include order `.clang-format`.  Use `clang-format` version 6.0.

Source/cmGeneratorTarget.h

@@ -5,11 +5,6 @@
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
-#include "cmLinkItem.h"
-#include "cmListFileCache.h"
-#include "cmPolicies.h"
-#include "cmStateTypes.h"
-
 #include <cstddef>
 #include <map>
 #include <set>
@@ -18,6 +13,11 @@
 #include <utility>
 #include <vector>
 
+#include "cmLinkItem.h"
+#include "cmListFileCache.h"
+#include "cmPolicies.h"
+#include "cmStateTypes.h"
+
 class cmComputeLinkInformation;
 class cmCustomCommand;
 class cmGlobalGenerator;