various bugfixes:
- erase flags variable if no flags are stored
- do not print false debug warning
- during activation do not overwrite activation flags
with persistent flags
This fixes crypt_keyslot_add_by_key where we were unable to store
keyslot (unbound to segment) with different key_size.
The code used (new) volume key size implicitly which could be wrong
if new size was not compatible with cipher parameter for keyslot area.
with json-c until 0.12.x json_object_array_length returned signed
integer. json-c 0.13.x and later changed return type to unsigned
size_t.
Consider return values less or equal to zero as empty array, otherwise
array is non-empty.
before this patch any LUKS2 requirement defined in header
would stop a restricted operation from proceeding further.
This patch adds ability to mask requirements (internal only).
