If you have a chat line with multiple lines that were scrolled so that
part of it is rendered at the bottom of the chat area, and part of it
falls below the chat area, there was a bug where the prefix_suffix would
be displayed at the end of the last line.
Looks like this happens because the gui_chat_display_prefix_suffix is
called for the line below the last line displayed in the chat area. So
we have to add a check for this so we don't add the prefix_suffix. This
check is copied from gui_chat_display_word which checks for the same.
Fixes#1912
Trygve Aaberge
8d430aa2eb