.NET 9.0 images with libc++ don't have all ABI header dependencies available

[jkoritzinsky]

To avoid building more than necessary, we tried to copy the libstdc++ cxxabi.h header into the libc++ include tree to enable the one project that uses it (dotnet/runtime's createdump).

I didn't do full validation of the images after making that change, and I missed that there are some dependencies of that header that aren't available.

We can do either of the following options:

• [ ] Copy more bits of the libstdc++ include directory into the libc++ include directory
• [ ] Update createdump to declare the ABI function it needs (which is well documented) itself instead of using the header declaration and remove the copied header.

I'm inclined to do the second option.

@sbomer what's your preference here?

[sbomer]

I'm fine with either option. Especially if it's just one ABI function then I'm inclined to agree, I'd pick the second option. What extra headers from libstdc++ would be required? Is it all of these?

/crossrootfs/arm/usr/include/arm-linux-gnueabihf/c++/5/bits/cxxabi_tweaks.h
/crossrootfs/arm/usr/include/c++/v1/cxxabi.h
/crossrootfs/arm/usr/include/c++/5/bits/cxxabi_forced.h
/crossrootfs/arm/usr/include/c++/5/cxxabi.h

[jkoritzinsky]

We'd need at least bits/c++-config.h as well (that's the one that the build failed on), and whatever else is included by the include chain.

With this failure and some other failures I'm seeing in CI that I expect to be related, I'm going to revert the stdlib PR and bring it back after having done more validation.

[jkoritzinsky]

Fixed by #1039