patch 8.1.1500: wrong shell command when building with VIMDLL and "!" in 'go'

Problem:    Wrong shell command when building with VIMDLL and "!" in
            'guioptions'.
Solution:   Add check for GUI in use. (Ken Takata)
diff --git a/src/version.c b/src/version.c
index 6635610..b0dcd3b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1500,
+/**/
     1499,
 /**/
     1498,