bpf programs: switch from integers to #define'd bpfloader versions

(per request from Lorenzo)

We do bump block/clatd/dscp_policy requirements from 0.12 to 0.13,
but this effectively doesn't matter:

- Beta2 is too old either way (pre-0.12)
- Beta3 is new enough (0.13)
- versions in between are simply obsolete / unused / not important
- bpfloader 0.12 won't boot right anyway due to lack of netd maps/programs
  (which cause a netd startup failure)

This allows us to have one less #define in the header files,
with a hard to write explanation about what exactly v0.12 is (or was).

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I1ecf15f9d7abbb82ec6bd49848255fab6a41aed4
6 files changed