zdir: check for errors
zdir: Check errors in constructor
zdir: assert constructors in test
zdir_patch: Check for errors in constructor
zdir_patch: asser constructors in test
zframe: assert constructor in test
zgossip: Check for errors
zgossip_msg: Check error in constructor
zgossip_msg: check for errors
zgossip_msg: assert constructors in test
zhash: Fix error checking in constructor
zhash: check for errors
zhash: assert constructors in test
zloop: Simplify error handling in constructor
zmonitor: Check errors in constructor
zmonitor: Assert constructors
zmonitor_v2: Improve error handing in constructors
zmonitor_v2: Fix socket leak in destructor
zmonitor_v2: Assert constructors in test
zmutex: Check allocation in constructor
zmutex: Assert constructor in test