IrcDecoder: restore irc_is_utf8()
IrcDecoder: restore irc_is_utf8()

gdamjan/communi-desktop,communi/communi-symbian,jpnurmi/communi-desktop,communi/communi-symbian,communi/communi-desktop,communi/communi-symbian,communi/communi-desktop,sevanteri/communi-desktop,communi/communi-symbian