patch 8.1.0701: sign message not translated and inconsistent spacing

Problem:    Sign message not translated and inconsistent spacing.
Solution:   Add _() for translation.  Add a space. (Ken Takata)  Also use
            MSG_BUF_LEN instead of BUFSIZ.

src/version.c

@@ -799,6 +799,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    701,
 /**/
     700,
 /**/