Add a `size_t count` argument to some `BNCustomArchitecture.free*` fields

[mkrasnitski]

Specifically, the freeFlagConditionsForSemanticFlagGroup and freeRegisterList fields should take an additional size_t count argument so that custom architectures implemented in other languages can correctly free the pointers passed to them through these functions without resorting to hackery (as discussed in #5654).

cc-ing @CouleeApps @KyleMiles