Method exchangeBitAnd

src/common/classes/fb_atomic.h:68–76

returns old value

	// returns old value
	counter_type exchangeBitAnd(counter_type val)
	{
		while (true)
		{
			counter_type oldVal = counter.load();
			if (counter.compare_exchange_strong(oldVal, oldVal & val))
				return oldVal;
		}
	}

	// returns old value
	counter_type exchangeBitOr(counter_type val)