The old definition only worked for functions that didn't use numbered
local labels. Upstream uses '666' not only as some kind of BSD in-joke,
but also because there's little likelihood of any function having
labels that high.
There's a wider question about whether we actually want to go via the
PLT at all in this code, but that's a question for another day.
(cherry-pick of 72d7e667c7e926cb120c4edb53cbf74c652ab915.)
Bug: 16906712
Change-Id: I3cd8ecc448b33f942bb6e783931808ef39091489
ca5b6a74a7