PATCH: silence build warning from libstdc++

[Ben Elliston]

On Thu, 2009-04-30 at 15:17 -0700, Benjamin Kosnik wrote:

> But, it looks valid to me just the same. Can you tell me how to
> reproduce? I would be surprised if this is the first you've seen of
> this, as the previous stdtr1c++.h include also had two choices for
> stdc++.h precompiled files.

I see it regularly on powerpc-linux and powerpc64-linux.

> Better would be to just edit include/Makefile.am to remove
> -Winvalid-pch from PCHFLAGS.

I'm OK with that if you are .. :-)

Ben