current status:

- only build s390x arch (see CMakeLists.txt)
- sample_s390x crash, due to qemu/target/s390x/cpu.c :: cpu_s390_init() still has bugs

Todo:

- fix qemu/target/s390x/cpu.c, so sample_s390x works
- enable building all arch to fix conflicts
- remove all static vars in qemu/target/s390x/translate.c [DONE in branch "static-vars"]
- support more registers in qemu/target/s390x/unicorn.c
- storage-keys needed?
- find & fix potential memory leaking with valgrind
- sync with "dev" branch of github unicorn