CLEANUP: lua: remove the session pointer from hlua_channel

It was only used to find what side the channel belongs to.
diff --git a/include/types/hlua.h b/include/types/hlua.h
index 88a8b8d..2275671 100644
--- a/include/types/hlua.h
+++ b/include/types/hlua.h
@@ -133,7 +133,6 @@
  */
 struct hlua_channel {
 	struct channel *chn;
-	struct session *s;
 };
 
 #else /* USE_LUA */
diff --git a/src/hlua.c b/src/hlua.c
index 1b6df67..0b82e92 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -2077,7 +2077,6 @@
 	chn = MAY_LJMP(lua_newuserdata(L, sizeof(*chn)));
 	lua_rawseti(L, -2, 0);
 	chn->chn = channel;
-	chn->s = s;
 
 	/* Pop a class sesison metatable and affect it to the userdata. */
 	lua_rawgeti(L, LUA_REGISTRYINDEX, class_channel_ref);