gpg: Fix use of deprecated RSA_E and RSA_E with newer libgcrypts.

* g10/misc.c (pubkey_get_npkey): Map RSA_E and RSA_S to RSA.
(pubkey_get_nskey): Ditto.
(pubkey_get_nsig): Ditto.
(pubkey_get_nenc): Ditto.
(pubkey_nbits): Take care of RSA_E and RSA_S.
--

The problem was that parse_key did not know about RSA_S and thus used
an opaque MPI which later crashed Libgcrypt. It is possible to fix
that also in Libgcrypt but we better do it here as well.

A test key using RSA_S is 0x98EEB6F7D87171CF.

Reported-by: Hanno Böck