Add %U XTOS extension for UUID/GUID string argument support

xtoskrnl/includes/rtli.h

@@ -312,6 +312,12 @@ XTSTATUS
 RtlpWriteWideCharacter(IN PRTL_PRINT_CONTEXT Context,
                        IN WCHAR Character);
 
+XTAPI
+XTSTATUS
+RtlpWriteWideStringCustomValue(IN PRTL_PRINT_CONTEXT Context,
+                               IN PCWSTR Format,
+                               IN ...);
+
 XTAPI
 XTSTATUS
 RtlpWriteWideStringIntegerValue(IN PRTL_PRINT_CONTEXT Context,