Refactor getdents.py, add support for SYS_getdents64

[dbgbgtf1]

Refactor getdents.py
SYS_getdents and SYS_getdents64 have different struct in kernel, but the getdent.py can only solve SYS_getdents struct
So I rewrite getdents.py and add support for SYS_getdents64

Changelog will be update later

[dbgbgtf1]

I just saw only major change should be include in changelog, so I will not update the changelog

[peace-maker]

Thanks! We've started to document every change in the change log, so this should be included too.

[dbgbgtf1]

But here says
This changelog only includes added major features and changes. Bugfixes and minor changes are omitted.

Should we remove that?

[RocketMaDev]

ping @peace-maker