patch 8.0.1537: xxd does not skip NUL lines when using ebcdic

Problem:    Xxd does not skip NUL lines when using ebcdic.
Solution:   Check for a NUL before converting a character for ebcdic. (Tim
            Sell, closes #2668)

src/version.c

@@ -778,6 +778,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1537,
 /**/
     1536,
 /**/