Don't use a plain %s when writing to a buffer

My compiler was understandably concerned about a potential buffer
overflow here. I don't think the string could get long enough to
cause that to happen, but it's hard to be certain. It's much safer
to limit the length of the string so that it fits in the buffer, as
done here, and if there really wasn't a problem the change will
cause no harm at all. (If there was, the string will be truncated
rather than corrupting memory. This code is in showing the
config-file version of a status highlight, something where
truncated text will probably be obvious to the user.)

src/botl.c

@@ -3163,7 +3163,9 @@ status_hilites_viewall()
     datawin = create_nhwindow(NHW_TEXT);
 
     while (hlstr) {
-        Sprintf(buf, "OPTIONS=hilite_status: %s", hlstr->str);
+        Sprintf(buf, "OPTIONS=hilite_status: %.*s",
+                (int)(BUFSZ - sizeof "OPTIONS=hilite_status: " - 1),
+                hlstr->str);
         putstr(datawin, 0, buf);
         hlstr = hlstr->next;
     }