vapi: write enumflag types to vapi headers

vapi: write enumflag types to vapi headers

Type: fix
Fixes: a51f9b3747

Some IPsec message type definitions were not being written to
ipsec.api.vapi.h. These include ipsec_sad_entry_add_del_v3 and
ipsec_sad_entry_add.

The cause appears to be that tunnel_flags, which is defined in
tunnel_types.api is a special case of enum called an enumflag. These do
not appear to have been handled in the code that generates the vapi
header files.

This patch adds processing of enumflag objects for vapi.

Change-Id: Ie506c4fcb5a07fe97a330ba11c252d1df98adfd9
Signed-off-by: Matthew Smith <mgsmith@netgate.com>