patch 9.0.1249: cannot export an abstract class

Problem:    Cannot export an abstract class. (Ernie Rael)
Solution:   Add the EX_EXPORT flag to :abstract. (closes #11884)
diff --git a/src/version.c b/src/version.c
index 52502b5..cb304ed 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1249,
+/**/
     1248,
 /**/
     1247,