[cfe-dev] Libc++ Windows fixes

[Ruben Van Boxem]

Hi guys,

I know this is more patchwork than it's currently worth, but every bit
helps of course!

Attached is some small fixes for libc++:
 - cerrno: like in Boost's cerrno, define the missing error constants
if they are undefined (which most of them are for Windows)
 - __locale: include the correct Windows headers to pull in the
correct constants and use those for Windows.
 - locale: don't include nl_types.h on windows, as it is unavailable
on that platform.

I hope I can get more fixes which are as trivial as these soon.

I do not have commit access (which seems to be a rarity around here),
and was told to shout loud for someone that would like to commit this.
so here it is:
SHOUT!
Please commit when you feel you're OK with it.

Thanks!

Ruben