pki: Support RSA verification using different hash algorithms

This changes the private API by adding one more argument to function

  pki_signature_from_blob()

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/pki.h

@@ -69,6 +69,7 @@ struct ssh_key_struct {
 
 struct ssh_signature_struct {
     enum ssh_keytypes_e type;
+    enum ssh_digest_e hash_type;
     const char *type_c;
 #ifdef HAVE_LIBGCRYPT
     gcry_sexp_t dsa_sig;