patch 8.1.0325: strings in swap file may not be NUL terminated

Problem:    Strings in swap file may not be NUL terminated. (Coverity)
Solution:   Limit the length of the used string.

src/version.c

@@ -794,6 +794,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    325,
 /**/
     324,
 /**/