Merge pull request #3230 from saraf/master

Fix build failure on ARM due to bad variable name

src/atomic_counter.hpp

@@ -188,7 +188,7 @@ class atomic_counter_t
                            "+Qo"(_value)
                          : "Ir"(decrement_), "r"(&_value)
                          : "cc");
-        return old_value - decrement != 0;
+        return old_value - decrement_ != 0;
 #elif defined ZMQ_ATOMIC_COUNTER_MUTEX
         sync.lock ();
         _value -= decrement_;