build: silence some MSVC warnings

4005 - about redefinition of `PLATFORM` symbol

align macros between dtrace and ETW removes warnings:
NODE\SRC\NODE_DTRACE.CC(180) : warning C4002: too many actual parameters for macro 'NODE_NET_SOCKET_READ'
NODE\SRC\NODE_DTRACE.CC(196) : warning C4002: too many actual parameters for macro 'NODE_NET_SOCKET_WRITE'

4996 - For the visible future I don't think we should be worried about the change in semantics of  `GetVersionEx`

4291 - for the `new` operator that has non side effects in FSReqWrap ```void *node::FSReqWrap::operator new(size_t,char *)```

4244 - This is a warning about truncation of an int64 to an int32 on ia32 builds. I don't believe there's much we can do about actually fixing it.