patch 8.2.3270: prop_find() finds property with ID -2

Problem:    prop_find() finds property with ID -2.
Solution:   Use a separate flag to indicate an ID was specified. (issue #8674)
diff --git a/src/version.c b/src/version.c
index e1e1f83..3f22663 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3270,
+/**/
     3269,
 /**/
     3268,