remove __x64_ prefix from 3.4

move error declaration above code for 3.4

Add linux_dirent struct block to PTREGS hook_getdents()

Fix for kernel versions <4.17 ...

The old linux_dirent struct isn't in the kernel headers anymore - even on 16.04
Declaring it manually allows us to copy the structure into kernel memory and dereference it later

3.4: tabs to spaces

working on support for < 4.17

update to use ftrace

add directory hiding