fix cff pass crash on llvm-9

delete unused decrypt fucntion

decrypt string and it's user only once

obfuscate constant string user

fix compatibility with llvm 8.x

run obfucation pass after global optimization

delete dead global variables

add simple c string encryption pass

delete CallerSlot if SecretArg is in use.

lower switch after flattening

using secret token to compute switch variable

porting ollvm flattening pass to goron

Add ollvm Flatttening pass

add indirect global variable obfuscation

add indirect call obfucastion