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)
diff --git a/src/version.c b/src/version.c
index 11fd817..116113b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    12,
+/**/
     11,
 /**/
     10,