genskel: Fix issues for C++ bindings v3
The C++ compiler is too much strict. It doesn't accept
valid C because fields are in the wrong order or missing.
- afb_verb_t generated structure invert vcbdata and session
- missing provide_class, require_class, require_api in the
afb_binding_v3 generated struct
The signature of the declared function was wrong.
- wrong verb's callback signature void fun(afb_req) instead of
void fun(afb_req_t)
This add the declaration of the (pre)initialization and onevent functions.
- missing init function signation generation, or probably preinit and
onevent (not tested those ones)
Bug-AGL: SPEC-1806
Change-Id: I1abf8a29f831ecc80458edcd3bd094b2108dc227
Signed-off-by: José Bollo <jose.bollo@iot.bzh>