libroot/arm: implement syscalls

Change-Id: Id9b37d29b802b7f469fb109054ec6446f93511b5
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4979
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

arm: added some missing arch bits and changed asm section for arm compat.

arm: added some missing arch bits and changed asm section for arm compat.