So far we jump through hoops everywhere to pass around osmo-hnbgw's
global singleton state to all code paths. Some files choose to spawn a
static "global" pointer. And we also have the talloc root tall_hnb_ctx.
Simplify:
- Have a single global g_hnbgw pointer. Drop all function args and
backpointers to the global state.
- Use that global g_hnbgw as talloc root context, instead of passing a
separate tall_hnb_ctx around.
(Cosmetic preparation for separate osmo_hnbgw_main.c file)
Change-Id: I3d54a5bb30c16a990c6def2a0ed207f60a95ef5d
Neels Hofmeyr
Neels Hofmeyr