patch 8.1.2018: using freed memory when out of memory and displaying message

Problem:    Using freed memory when out of memory and displaying message.
Solution:   Make a copy of the message first.
diff --git a/src/version.c b/src/version.c
index c6f60af..3161360 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2018,
+/**/
     2017,
 /**/
     2016,