core: Use 64 bit instead of gpgme_off_t for some internal functions.
* src/conversion.c (_gpgme_string_to_off): Return an u64 value. * src/data.c (_gpgme_data_get_size_hint): Ditto. (gpgme_data_set_flag): Use u64 for io-buffer-size due to string_to_off change. * src/data.h (struct gpgme_data): Change size_hint to u64. * src/engine-gpg.c (add_input_size_hint): Replace gpgme_off_t by u64.
- GnuPG-bug-id: T6534