Remove duplicated prototypes.

* src/gcrypt-int.h (_gcry_mpi_ec_new, _gcry_mpi_ec_set_mpi)
(gcry_mpi_ec_set_point): Remove.

Thos used gpg_error_t instead of gpg_err_code_t and the picky AIX
compiler takes this as a severe error.

• Signed-off-by: Werner Koch <wk@gnupg.org>