ecdh: Use bignum_bin2bn.
ecdh: Check if we have ECC support.
tests: Fix a valgrind warning.
tests: Try to fix valgrind warnings.
packet: Remove logically dead code.

CID #1128796
examples: Fix else branch.

CID #1127816
curve25519: Fix a memory leak.

CID #1125257
curve25519: Do not leak q_s_string.

CID #1125256
curve25519: Fix memory leaks in ssh_server_curve25519_init().

CID #1125255
pki_gcrypt: Add pki_private_key_to_pem() stub.
pki_crypto: Add pki_private_key_to_pem().
pki: Add ssh_pki_import_privkey_file().
tests: Add torture_pki_write_privkey_rsa test.
tests: Add torture_pki_write_privkey_dsa test.
tests: Add torture_pki_write_privkey_ecdsa test.