patch 9.0.1213: adding a line below the last one does not expand fold

Problem:    Adding a line below the last one does not expand fold.
Solution:   Do not skip mark_adjust() when adding lines below the last one.
            (Brandon Simmons, closes #11832, closes #10698)
diff --git a/src/testdir/test_fold.vim b/src/testdir/test_fold.vim
index f915a66..7f75e91 100644
--- a/src/testdir/test_fold.vim
+++ b/src/testdir/test_fold.vim
Binary files differ