SysCalls 177 sys_spu_thread_group_terminate

Warning: **lack of material** to trigger sys_spu_thread_group_* calls. (should meet the definition)
Added State changes for sys_spu_thread_group_* calls.
Does almost nothing for 176 and skips the EPERM check for 177.

* If you think *this should not be merged now*, **please comment** to tell me about why please.
* If you think *my code doesn't meet the definition* of the call, **please comment** to let me know.

Also thank @Nekotekina for pointing some mistakes i've ever made. @BlackDaem, thank you too.
And. Thank you guy for your reading this pull.

- [x] misunderstood comments removed.
- [x] use space instead of tab in syscall.cpp.
- [x] use of group_info->lock removed or commented.
- [x] try implement the call strictly following definition.
- [ ] Trigger this call to test it throughoutly.
- [x] commit of this call merged to a single one.