patch 8.1.2334: possible NULL pointer dereference in popup_locate()

Problem:    Possible NULL pointer dereference in popup_locate(). (Coverity)
Solution:   Check for NULL pointer.
diff --git a/src/version.c b/src/version.c
index 9037349..c327f98 100644
--- a/src/version.c
+++ b/src/version.c
@@ -738,6 +738,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2334,
+/**/
     2333,
 /**/
     2332,