patch 8.0.0871: status line for a terminal window always has "[+]".

Problem:    The status line for a terminal window always has "[+]".
Solution:   Do make the status line include "[+]" for a terminal window.
diff --git a/src/screen.c b/src/screen.c
index 77d0e4f..fb7c3ce 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -6893,7 +6893,11 @@
 	    len += (int)STRLEN(p + len);
 	}
 #endif
-	if (bufIsChanged(wp->w_buffer))
+	if (bufIsChanged(wp->w_buffer)
+#ifdef FEAT_TERMINAL
+		&& !bt_terminal(wp->w_buffer)
+#endif
+		)
 	{
 	    STRCPY(p + len, "[+]");
 	    len += 3;