build, windows: fixed x64 configuration issue

Backported from master 8010bf9
build, windows: do not fail on Windows SDK Prompt

Backported from master 2f6d4b4
process: don't close stdio fds during spawn

This is needed when closed stdio fd is reused for uv_spawn pipe.
Fixes #1211
Merge branch 'v0.10'

Conflicts:
	src/unix/process.c
unix: fallback to blocking writes if reopening a tty fails

In case reopening the file descriptor fails, fallback to the old
behavior where we do blocking writes, to avoid disrupting other
processes potentially using the file descriptor.
unix, windows: add IPv6 support for uv_udp_multicast_interface