[Interest] rvalue references on Mac OS X 10.10 and XCode 7

[Philippe]

> If you have some old library that needs libstdc++, then you're stuck with it 
> for now. That means you must tell your linker not to use libc++, so you need 
> to ensure that the -stdlib=libstdc++ is passed to all steps of the build 
> (compiler and linker). Otherwise you'll get the linker errors you mentioned.

No, I do use libc++ also.
And for some reason, I don't have problems linking with libstdc++ *also*.

In my xcode config file, I have both:
CLANG_CXX_LIBRARY = libc++
OTHER_LDFLAGS = $SDKROOT/usr/lib/libstdc++.dylib

I must be doing that for maybe 2 or 3 years.

> > But __GNUC_LIBSTD__ is not defined, hence Q_COMPILER_RVALUE_REFS is
> > #defined.
> 
> It's defined somewhere in libstdc++ headers.

I don't include any of these headers, hence it's not defined for my
application.

Philippe