Explicitly initialize POD struct fields.

[ni4]

Description

As from discussion at https://github.com/rnpgp/rnp/pull/1109#issuecomment-624612517 we should {} - initialize all struct fields to avoid possible further initialization errors.

[antonsviridenko]

maybe just memset(&s, 0, sizeof some_struct_t); ?

[dewyatt]

maybe just memset(&s, 0, sizeof some_struct_t); ?

It's not very C++-y, it relies on all members remaining POD, and it seems maybe more likely to be a runtime vs compile-time thing.

[ni4]

maybe just memset(&s, 0, sizeof some_struct_t); ?

That will not work within the migration to C++, when, for instance, list variables will become a std::vector or std::map.

[rrrooommmaaa]

So, I'm going to replace calloc with new and free with delete, right?

[rrrooommmaaa]

for all these:

• rnp_ffi_st
• rnp_key_handle_st
• rnp_uid_handle_st
• rnp_signature_handle_st
• rnp_recipient_handle_st
• rnp_symenc_handle_st
• rnp_input_st
• rnp_output_st
• rnp_op_generate_st
• rnp_op_sign_st
• rnp_op_sign_signature_st
• rnp_op_verify_signature_st
• rnp_op_verify_st
• rnp_op_encrypt_st
• rnp_identifier_iterator_st

[ni4]

Please not yet, if possible - I have some postponed code which will definitely conflict with those changes (see https://github.com/ni4/rnp/pull/4)