I am not sure this is the correct solution.

The problem seems to be that the RRH GW does not use ITTI
and thus the type 'as_nas_info_t' is not defined, and then
the compilation fails.

The simple fix is to include 'as_message.h' in
'openair2/RRC/LITE/defs.h' if ENABLE_ITTI is not
defined. Maybe it's not good. RRH GW compiles with this fix.