[MLton] A few patches we had to apply to port from version 20030716 to 20051202 and for the MinGW port

[Nicolas Bertolotti]

> The initialization occurs only once; the MLton_initSockets function (see
> runtime/platform/mingw.c) includes a static variable that ensures that
> WSAStartup is only called once.
> 

There is a small cost anyway as the MLton_initSockets() function itself is
called multiple times and does a test ;-) it is still possible to optimize
...