patch 8.1.2033: cannot build with tiny features

Problem:    Cannot build with tiny features.
Solution:   Add #ifdef.
diff --git a/src/screen.c b/src/screen.c
index fec1081..14b9465 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -5383,9 +5383,11 @@
 		&& draw_state == WL_LINE
 		&& !attr_pri)
 	{
+#ifdef LINE_ATTR
 	    if (line_attr)
 		char_attr = hl_combine_attr(extra_attr, line_attr);
 	    else
+#endif
 		char_attr = extra_attr;
 	}