The variable decrement was changed to decrement_
in c581f43c

In -one- place, it remained as decrement
and gives:

In file included from src/ctx.hpp:44:0,
from src/address.cpp:33:
src/atomic_counter.hpp: In member function 'bool zmq::atomic_counter_t::sub(zmq::atomic_counter_t::integer_t)':
src/atomic_counter.hpp:191:28: error: 'decrement' was not declared in this scope

Changing it to decrement_ fixes the problem.