MFC r287649:
Use a common subroutine to fetch and zero protocol stats instead of
duplicating roughly similar code for each protocol.

Merge r261582, r261601, r261610, r261613, r261627, r261640, r261641, r261823,
r261825, r261859, r261875, r261883, r261911, r262027, r262028, r262029,
r262030, r262162 from head.

Large flowtable revamp. See commit messages for merged revisions for
details.

Sponsored by: Netflix

Merge r261582, r261601, r261610, r261613, r261627, r261640, r261641, r261823,
r261825, r261859, r261875, r261883, r261911, r262027, r262028, r262029,
r262030, r262162 from head.

Large flowtable revamp. See commit messages for merged revisions for
details.

Sponsored by: Netflix