patch 8.1.0917: double free when running out of memory

Problem:    Double free when running out of memory.
Solution:   Remove one free. (Ken Takata, closes #3955)
diff --git a/src/version.c b/src/version.c
index 7614566..9a31c2f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    917,
+/**/
     916,
 /**/
     915,