simplified menu_headings fix

Reported by entrez, some putstr() to text window got changed to
add_menu_str().  I didn't test with curses; with tty some headers
ended up in limbo:  "Artifacts" header for '` a y' (wizard mode show
artifacts, something I had forgotten even existed) and also monster
class headers for 'm #vanquished by-class' (available to everyone).
Qt lost them too, but at least it didn't panic.

Not due to over-simplification:  end of game disclosure suppresses
header line highlighting, except when disclosing final inventory.
Change it to do so, although it would be simpler overall to just not
bother with any menu_headings highlight suppression.

src/artifact.c

@@ -1071,7 +1071,8 @@ dump_artifact_info(winid tmpwin)
     int m;
     char buf[BUFSZ], buf2[BUFSZ];
 
-    add_menu_heading(tmpwin, "Artifacts");
+    /* not a menu, but header uses same bold or whatever attribute as such */
+    putstr(tmpwin, iflags.menu_headings, "Artifacts");
     for (m = 1; m <= NROFARTIFACTS; ++m) {
         Snprintf(buf2, sizeof buf2,
                 "[%s%s%s%s%s%s%s%s%s]", /* 9 bits overall */