elf.h: update EM_ elf machine defines and add R_BPF_ defines

sync with gabi: http://www.sco.com/developers/gabi/latest/ch4.eheader.html

EM_BPF is new in linux v4.8 and officially assigned:
https://lists.iovisor.org/pipermail/iovisor-dev/2016-June/000266.html
added related relocs too.
1 file changed