zmq @4.2.0 does not build on a PPC running OS X 10.5.8

[josephsacco]

The latest version of zmq does not build on a PPC running leopard. The previous version, 4.1.6_0, builds without incident.

The problem is CLOCK_MONOTONIC is not defined in time.h for OSX 10.5.8[see snippet of build output below].

-Joseph

src/clock.cpp: In static member function 'static uint64_t zmq::clock_t::rdtsc()': src/clock.cpp:243:19: error: 'CLOCK_MONOTONIC' was not declared in this scope

clock_gettime(CLOCK_MONOTONIC, &ts);

src/clock.cpp:243:39: error: 'clock_gettime' was not declared in this scope

clock_gettime(CLOCK_MONOTONIC, &ts);