rfc: WIN32 vs _WIN32 and more

[Alan Coopersmith]

On 5/17/19 1:08 AM, walter harms wrote:
> I found also:
> ISC  *
> MOTOROLA *
> VMS    *
> USG    *
> sgi
> ultrix *
> __osf__ *

We've removed a bunch of code using those defines already (I've mostly
used #unifdef to do so, with manual editing only for special cases).

We still need the #ifdefs for sun & sparc, but prefer the __sun & __sparc
forms so they still work in strict standards compliance mode.

-- 
	-Alan Coopersmith-               alan.coopersmith at oracle.com
	 Oracle Solaris Engineering - https://blogs.oracle.com/alanc