libstdc++-v3 won't build on IRIX 5.2

[Benjamin Kosnik]

> I see these macros aren't available on IRIX 6.3 either.  Is there any
> reason for not using generic/ctype_base.h, given that most IRIX
> versions don't have these macros available?

No.

> Alternatively, we could probably #ifndef/#define these macros on
> the irix-specific version of ctype_base.h.

Ugh. Don't do this. If you're going down this road, make versioned irix 
folders, like solaris.

-benjamin