Remove store.

Rebased and merged by me, with Ben's approval.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Ben Laurie <ben@openssl.org>

crypto/engine/eng_lib.c

@@ -89,7 +89,6 @@ void engine_set_all_null(ENGINE *e)
     e->dsa_meth = NULL;
     e->dh_meth = NULL;
     e->rand_meth = NULL;
-    e->store_meth = NULL;
     e->ciphers = NULL;
     e->digests = NULL;
     e->destroy = NULL;