MINOR: ssl: reach a ckch_store from a sni_ctx

It was only possible to go down from the ckch_store to the sni_ctx but
not to go up from the sni_ctx to the ckch_store.

To allow that, 2 pointers were added:

- a ckch_inst pointer in the struct sni_ctx
- a ckckh_store pointer in the struct ckch_inst
2 files changed