patch 8.0.1571: can't build without GUI

Problem:    Can't build without GUI.
Solution:   Adjust #ifdef for gui_find_menu().
diff --git a/src/version.c b/src/version.c
index 6f498aa..2f045e4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1571,
+/**/
     1570,
 /**/
     1569,