Implement BlEfiDirectorySeparator() routine for setting correct EFI directory separator

xtldr/includes/xtbl.h

@@ -10,8 +10,7 @@
 #define __XTLDR_XTBL_H
 
 #include <xtkmapi.h>
-#include <bldefs.h>
-#include <blproto.h>
+#include <blmod.h>
 #include <xtver.h>
 
 
@@ -52,6 +51,9 @@ VOID
 BlDbgPrint(IN PUINT16 Format,
            IN ...);
 
+VOID
+BlEfiDirectorySeparator(IN OUT PUCHAR Path);
+
 INT_PTR
 BlEfiGetSecureBootStatus();