patch 9.0.0012: signature files not detected properly

Problem:    Signature files not detected properly.
Solution:   Add a function to better detect signature files. (Doug Kearns)

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    12,
 /**/
     11,
 /**/