irc: do not translate string "Msg" for messages to channel ops/voiced

src/plugins/irc/irc-command.c

@@ -2593,7 +2593,7 @@ irc_command_msg (void *data, struct t_gui_buffer *buffer, int argc,
                                                  "notify_none,no_highlight",
                                                  "%s%s%s -> %s%s%s: %s",
                                                  weechat_prefix ("network"),
-                                                 _("Msg"),
+                                                 "Msg",
                                                  IRC_COLOR_RESET,
                                                  IRC_COLOR_CHAT_CHANNEL,
                                                  targets[i],

src/plugins/irc/irc-protocol.c

@@ -1539,7 +1539,7 @@ IRC_PROTOCOL_CALLBACK(privmsg)
                                                         nick),
                                      "%s%s%s%s(%s%s%s)%s: %s",
                                      weechat_prefix ("network"),
-                                     _("Msg"),
+                                     "Msg",
                                      (msg_op) ? "Op" : ((msg_voice) ? "Voice" : ""),
                                      IRC_COLOR_CHAT_DELIMITERS,
                                      irc_nick_color_for_message (server, ptr_nick, nick),