Wip strong claim#1

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mattbenjamin wants to merge 4 commits intoupstream-1202from

wip-strong-claim

Commits on Dec 2, 2014

Add "strong" claim to buffer::list and buffer::ptr.
Matt Benjamin
committed
Restore zero-copy buffers in OSD fast path.
Matt Benjamin
committed
Message::set_data cannot preserve constness.
Matt Benjamin
committed
Include common/likely.h in buffer.h
Matt Benjamin
committed