Add various functions to allocate and set the fields of an ECDSA_METHOD
structure.
(cherry picked from commit 94c2f77a62be7079ab1893ab14b18a30157c4532)
- hide the EC_KEY structure definition in ec_lcl.c + add
some functions to use/access the EC_KEY fields
- change the way how method specific data (ecdsa/ecdh) is
attached to a EC_KEY
- add ECDSA_sign_ex and ECDSA_do_sign_ex functions with
additional parameters for pre-computed values
- rebuild libeay.num from 0.9.7
