irc: restore irc raw filter after /upgrade (issue #1000)

src/plugins/irc/irc-upgrade.c

@@ -894,6 +894,7 @@ irc_upgrade_load ()
 {
     int rc;
     struct t_upgrade_file *upgrade_file;
+    const char *ptr_filter;
 
     irc_upgrade_set_buffer_callbacks ();
 
@@ -906,5 +907,13 @@ irc_upgrade_load ()
 
     weechat_upgrade_close (upgrade_file);
 
+    if (irc_raw_buffer)
+    {
+        ptr_filter = weechat_buffer_get_string (irc_raw_buffer,
+                                                "localvar_filter");
+        if (ptr_filter && ptr_filter[0])
+            irc_raw_filter_options (ptr_filter);
+    }
+
     return rc;
 }