Does US gold reserves includes other counties' gold reserves?
No.  

The $8,133.5$ tonnes of gold, i.e. $261,498,926.230$ fine troy ounces, of the U.S. Government owned gold reserve is detailed in a monthly status report produced by the US Department of the Treasury, with the latest figure being for August 31, 2016.

The weight and notional value of $\$11$ billion (based on a statutory rate of $\$42.2222$ per Fine Troy Ounce) have change by very small amounts in recent years, I would guess related to selling gold coins and buying stock to make them.  For example the total in January 2012 was $261,498,899.316$ fine troy ounces, a difference of about $27$ troy ounces from the current figure.   

Gold belonging to other countries are stored in the US, particularly in New York as being convenient for the market and for transport. But this is not counted in the US Treasury report.