MyNewt on Windows

[Shiraz Nisar]

Hi All,

It seems we will be not be able to build MyNewt on windows environment
using mingw.

function sigprocmask (SIG_UNBLOCK, &s, (sigset_t *) 0*  is not available.

http://sourceforge.net/p/mingw-w64/support-requests/92/

I think documentation should be updated.

Thanks,

Shiraz