Previously all types are compound. This adds support for aliases,
so one can do things like:
typedef u32 interface_index;
or
typedef u8 ip4_address[4];
Change-Id: I0455cad0123fc88acb491d2a3ea2725426bdb246
Signed-off-by: Ole Troan <ot@cisco.com>
Signed-off-by: Klement Sekera <ksekera@cisco.com>