Remove last remains of the former module system.
* src/gcrypt-module.h, src/module.c: Remove. * src/visibility.h: Do not include gcrypt-module.h. * src/g10lib.h: Remove all prototypes from module.c (gcry_module): Remove. * cipher/cipher-internal.h (gcry_cipher_handle): Remove unused field.
- Signed-off-by: Werner Koch <wk@gnupg.org>