cmd/bpf2go: output ELF .o next to the .go file
cmd/bpf2go: output ELF .o next to the .go file

Go 1.16 will add file embedding via magic comments, which we can use to
store the .o file instead of stuffing it into a global. Move the
compiled object file next to the .go to simplify this in the future.

cilium/ebpf,cilium/ebpf