Re-implemented SP800Derive in C++, which is added as the new key
derivation function in Android 9.0 May update. From file
services/core/java/com/android/server/locksettings/SP800Derive.java in
frameworks/base.
This is required to get TWRP working on any Android device that has a
screen lock set up after the May update.
Change-Id: I5c1a51b110033f2b0b75d5e36fd8098c05e95179