ebpf_common.h should not include linux/bpf.h

[mihaibudiu]

We do not need to depend on any kernel headers when doing user-level testing.

[mihaibudiu]

@fruffy: this may be easy to do

[fruffy]

Yeah it is a quick fix, but I have to copy some data structures from the bpf file. Primarily these:

/* flags for BPF_MAP_UPDATE_ELEM command, copied from "linux/bpf" */
#define BPF_ANY     0 /* create new element or update existing */
#define BPF_NOEXIST 1 /* create new element if it didn't exist */
#define BPF_EXIST   2 /* update existing element */
#define BPF_F_LOCK  4 /* spin_lock-ed map_lookup/map_update */

/* Support bpf map types */
enum bpf_map_type {
    BPF_MAP_TYPE_HASH,
    BPF_MAP_TYPE_ARRAY,

I am currently working on a branch which restructures the ebpf backend a bit. I will include that change.