Start on support for aarch64
- Start aarch64 support
- crt0 - add support to _start
- platform - aarch64 does not have the open syscall. Instead most libc implementations use openat() with AT_FDCWD
- Use sc instead of syscall. sc is the maintained fork of syscall.
I'd like to get this working on my rpi3. I still need to add support to
the va_list
crate for aarch64
. Tests pass with all stdio
stuff
commented out.