patch 9.0.1232: ColorTable saving and restoring does not work properly

Problem:    ColorTable saving and restoring does not work properly.
Solution:   Restore ColorTable[16] usage. (Christopher Plewright,
            closes #11836)
diff --git a/src/term.c b/src/term.c
index ab42afb..54da3d7 100644
--- a/src/term.c
+++ b/src/term.c
@@ -3222,7 +3222,7 @@
     vim_snprintf(buf, MAX_COLOR_STR_LEN,
 				  (char *)s, RED(rgb), GREEN(rgb), BLUE(rgb));
 #ifdef FEAT_VTP
-    if (has_vtp_working())
+    if (use_wt())
     {
 	out_flush();
 	buf[1] = '[';