patch 8.2.1974: Vim9: test for has('gui_running') fails with VIMDLL

Problem:    Vim9: test for has('gui_running') fails with VIMDLL.
Solution:   Adjust the #ifdef. (Ken Takata, closes #7276)
diff --git a/src/version.c b/src/version.c
index 8535ac5..06fa4d0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1974,
+/**/
     1973,
 /**/
     1972,