patch 9.0.1649: syntax test failure causes script to abort

Problem:    Syntax test failure causes script to abort.
Solution:   Fix appending string to list.
diff --git a/runtime/syntax/testdir/runtest.vim b/runtime/syntax/testdir/runtest.vim
index 9e2739f..27b7664 100644
--- a/runtime/syntax/testdir/runtest.vim
+++ b/runtime/syntax/testdir/runtest.vim
@@ -163,7 +163,7 @@
 
       call delete('done/' .. root)
 
-      call failed_tests->extend(root)
+      eval failed_tests->add(root)
       if len(failed_tests) > MAX_FAILED_COUNT
 	call Message('')
 	call Message('Too many errors, aborting')
diff --git a/src/version.c b/src/version.c
index 191bf50..5535b9a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1649,
+/**/
     1648,
 /**/
     1647,