This also fixes the elixir suite by using
Trust me on this one - or you can build your own Windows instance if you want...
Unfortuantely, os:timestamp() on Windows only has millisecond accuracy. That means that the two Mango tests checking for a positive value of execution_time fail, since these tests appear to be running in <1ms on my test setup (a rather anemic Windows VM!) This change disables only the check for execution_time in two tests, and leaves the remainder of the execution_stats checks in place on Windows. It also introduces a convenience "make.cmd" file so you can "make check" without typing "make -f Makefile.win check" all the time.