Add missing C++ ABI linker flag for AIX

[uyoyo0]

This PR resolves a linking failure when building C++ code on AIX. For example, when working with a downstream crate like cxx, cargo test fails during the linking stage with the following error:

ld: 0711-317 ERROR: Undefined symbol: __xlcxx_personality_v1

The current implementation links against libc++ but we additionally need it to link against libc++abi which is what this patch does.

[NobodyXu]

Hmm does enabling Build::cpp not working?

[uyoyo0]

Hmm does enabling Build::cpp not working?

It correctly identifies libc++ but the issue is that it fails to identify and link libc++abi which contains symbols for things such as exception handling.

[NobodyXu]

It correctly identifies libc++ but the issue is that it fails to identify and link libc++abi which contains symbols for things such as exception handling.

That's strange, based on my experience of using c++ with gcc/clang, using the c++ compiler automatically link in stdc++ and other stuff required, including exception handling.

cc @madsmtm wdyt

[uyoyo0]

Hi @NobodyXu @madsmtm, just a friendly ping to see if you've had the chance to look further into this.

[NobodyXu]

Still not sure if aix needs cxxabi, because usually linking with libstdc++ or libcxx is suffice

https://stackoverflow.com/questions/20357033/usr-lib-x86-64-linux-gnu-libstdc-so-6-version-cxxabi-1-3-8-not-found

Maybe you didn't add cxxabi to LD_LIBRARY_PATH or it's not in the path where the dynamic linkr can find?

[madsmtm]

I tend to think it's fine to add this, AIX is kind of a weird target (with a whole other set of C compilers), not surpised that it requires something like this.

But I guess we could ping powerpc64-ibm-aix target maintainers and see what they think?
@daltenty @gilamn5tr @amy-kwan

Btw @uyoyo0, what compiler are you using? Is this only a problem when using XL, or is it needed when using Clang too?

[madsmtm]

Nit:

Suggested change

	if self.get_target()?.os == "aix" {
	if target.os == "aix" {