gpgsm: Support signing using ECDSA.
* sm/gpgsm.h (struct certlist_s): Add helper field pk_algo. * sm/sign.c (gpgsm_sign): Store the public key algo. Take the hash algo from the curve. Improve diagnostic output in verbose mode.
Backported-from-master: f44d395bdfec464b1e2a0a1aef39561e6e48a45c