patch 9.0.0608: with spelling, deleting a full stop does not update next line

Problem:    With spell checking, deleting a full stop at the end of a line
            does not update SpellCap at the start of the next line.
Solution:   Update the next line when characters have been deleted.  Also when
            using undo.
diff --git a/src/change.c b/src/change.c
index 038f3c1..67b7023 100644
--- a/src/change.c
+++ b/src/change.c
@@ -709,6 +709,13 @@
     changedOneline(curbuf, lnum);
     changed_common(lnum, col, lnum + 1, 0L);
 
+#ifdef FEAT_SPELL
+    // When text has been changed at the end of the line, possibly the start of
+    // the next line may have SpellCap that should be removed or it needs to be
+    // displayed.  Schedule the next line for redrawing just in case.
+    if (spell_check_window(curwin) && lnum < curbuf->b_ml.ml_line_count)
+	redrawWinline(curwin, lnum + 1);
+#endif
 #ifdef FEAT_DIFF
     // Diff highlighting in other diff windows may need to be updated too.
     if (curwin->w_p_diff)